library

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:x: test/3_yukicoder/686.test.cpp

Depends on

Code

#define PROBLEM "https://yukicoder.me/problems/no/686"
#include "my_template.hpp"
#include "other/io.hpp"
#include "alg/acted_monoid/max_add.hpp"
#include "ds/randomized_bst/rbst_acted_monoid.hpp"

void solve() {
  LL(N);
  using AM = ActedMonoid_Max_Add<int>;
  RBST_ActedMonoid<AM, false> X(1 + N);
  using np = decltype(X)::np;

  np root = X.new_node(infty<int>);

  FOR(N) {
    if (X.prod(root) != infty<int>) root = X.merge(root, X.new_node(infty<int>));
    LL(L, R);
    // L未満 / R 未満
    np a, b, c, c1, c2;
    auto check_L = [&](int e) -> bool { return e < L; };
    auto check_R = [&](int e) -> bool { return e < R; };
    tie(a, root) = X.split_max_right(root, check_L);
    tie(b, c) = X.split_max_right(root, check_R);
    tie(c1, c2) = X.split(c, 1);
    b = X.apply(b, 1);
    c1 = X.set(c1, 0, L);
    root = X.merge4(a, c1, b, c2);
  }
  auto check = [&](int e) -> bool { return e < infty<int>; };
  auto [n1, n2] = X.split_max_right(root, check);
  int ANS = (n1 ? n1->size : 0);
  print(ANS);
}

signed main() {
  solve();
  return 0;
}
#line 1 "test/3_yukicoder/686.test.cpp"
#define PROBLEM "https://yukicoder.me/problems/no/686"
#line 1 "my_template.hpp"
#if defined(LOCAL)
#include <my_template_compiled.hpp>
#else

// https://codeforces.com/blog/entry/96344
#pragma GCC optimize("Ofast,unroll-loops")
// いまの CF だとこれ入れると動かない？
// #pragma GCC target("avx2,popcnt")

#include <bits/stdc++.h>

using namespace std;

using ll = long long;
using u8 = uint8_t;
using u16 = uint16_t;
using u32 = uint32_t;
using u64 = uint64_t;
using i128 = __int128;
using u128 = unsigned __int128;
using f128 = __float128;

template <class T>
constexpr T infty = 0;
template <>
constexpr int infty<int> = 1'010'000'000;
template <>
constexpr ll infty<ll> = 2'020'000'000'000'000'000;
template <>
constexpr u32 infty<u32> = infty<int>;
template <>
constexpr u64 infty<u64> = infty<ll>;
template <>
constexpr i128 infty<i128> = i128(infty<ll>) * 2'000'000'000'000'000'000;
template <>
constexpr double infty<double> = infty<ll>;
template <>
constexpr long double infty<long double> = infty<ll>;

using pi = pair<ll, ll>;
using vi = vector<ll>;
template <class T>
using vc = vector<T>;
template <class T>
using vvc = vector<vc<T>>;
template <class T>
using vvvc = vector<vvc<T>>;
template <class T>
using vvvvc = vector<vvvc<T>>;
template <class T>
using vvvvvc = vector<vvvvc<T>>;
template <class T>
using pq = priority_queue<T>;
template <class T>
using pqg = priority_queue<T, vector<T>, greater<T>>;

#define vv(type, name, h, ...) vector<vector<type>> name(h, vector<type>(__VA_ARGS__))
#define vvv(type, name, h, w, ...) vector<vector<vector<type>>> name(h, vector<vector<type>>(w, vector<type>(__VA_ARGS__)))
#define vvvv(type, name, a, b, c, ...) \
  vector<vector<vector<vector<type>>>> name(a, vector<vector<vector<type>>>(b, vector<vector<type>>(c, vector<type>(__VA_ARGS__))))

// https://trap.jp/post/1224/
#define FOR1(a) for (ll _ = 0; _ < ll(a); ++_)
#define FOR2(i, a) for (ll i = 0; i < ll(a); ++i)
#define FOR3(i, a, b) for (ll i = a; i < ll(b); ++i)
#define FOR4(i, a, b, c) for (ll i = a; i < ll(b); i += (c))
#define FOR1_R(a) for (ll i = (a)-1; i >= ll(0); --i)
#define FOR2_R(i, a) for (ll i = (a)-1; i >= ll(0); --i)
#define FOR3_R(i, a, b) for (ll i = (b)-1; i >= ll(a); --i)
#define overload4(a, b, c, d, e, ...) e
#define overload3(a, b, c, d, ...) d
#define FOR(...) overload4(__VA_ARGS__, FOR4, FOR3, FOR2, FOR1)(__VA_ARGS__)
#define FOR_R(...) overload3(__VA_ARGS__, FOR3_R, FOR2_R, FOR1_R)(__VA_ARGS__)

#define all(x) x.begin(), x.end()
#define len(x) ll(x.size())
#define elif else if

#define eb emplace_back
#define mp make_pair
#define mt make_tuple
#define fi first
#define se second

#define stoi stoll

int popcnt(int x) { return __builtin_popcount(x); }
int popcnt(u32 x) { return __builtin_popcount(x); }
int popcnt(ll x) { return __builtin_popcountll(x); }
int popcnt(u64 x) { return __builtin_popcountll(x); }
int popcnt_sgn(int x) { return (__builtin_parity(unsigned(x)) & 1 ? -1 : 1); }
int popcnt_sgn(u32 x) { return (__builtin_parity(x) & 1 ? -1 : 1); }
int popcnt_sgn(ll x) { return (__builtin_parityll(x) & 1 ? -1 : 1); }
int popcnt_sgn(u64 x) { return (__builtin_parityll(x) & 1 ? -1 : 1); }
// (0, 1, 2, 3, 4) -> (-1, 0, 1, 1, 2)
int topbit(int x) { return (x == 0 ? -1 : 31 - __builtin_clz(x)); }
int topbit(u32 x) { return (x == 0 ? -1 : 31 - __builtin_clz(x)); }
int topbit(ll x) { return (x == 0 ? -1 : 63 - __builtin_clzll(x)); }
int topbit(u64 x) { return (x == 0 ? -1 : 63 - __builtin_clzll(x)); }
// (0, 1, 2, 3, 4) -> (-1, 0, 1, 0, 2)
int lowbit(int x) { return (x == 0 ? -1 : __builtin_ctz(x)); }
int lowbit(u32 x) { return (x == 0 ? -1 : __builtin_ctz(x)); }
int lowbit(ll x) { return (x == 0 ? -1 : __builtin_ctzll(x)); }
int lowbit(u64 x) { return (x == 0 ? -1 : __builtin_ctzll(x)); }

template <typename T>
T kth_bit(int k) {
  return T(1) << k;
}
template <typename T>
bool has_kth_bit(T x, int k) {
  return x >> k & 1;
}

template <typename UINT>
struct all_bit {
  struct iter {
    UINT s;
    iter(UINT s) : s(s) {}
    int operator*() const { return lowbit(s); }
    iter &operator++() {
      s &= s - 1;
      return *this;
    }
    bool operator!=(const iter) const { return s != 0; }
  };
  UINT s;
  all_bit(UINT s) : s(s) {}
  iter begin() const { return iter(s); }
  iter end() const { return iter(0); }
};

template <typename UINT>
struct all_subset {
  static_assert(is_unsigned<UINT>::value);
  struct iter {
    UINT s, t;
    bool ed;
    iter(UINT s) : s(s), t(s), ed(0) {}
    int operator*() const { return s ^ t; }
    iter &operator++() {
      (t == 0 ? ed = 1 : t = (t - 1) & s);
      return *this;
    }
    bool operator!=(const iter) const { return !ed; }
  };
  UINT s;
  all_subset(UINT s) : s(s) {}
  iter begin() const { return iter(s); }
  iter end() const { return iter(0); }
};

template <typename T>
T floor(T a, T b) {
  return a / b - (a % b && (a ^ b) < 0);
}
template <typename T>
T ceil(T x, T y) {
  return floor(x + y - 1, y);
}
template <typename T>
T bmod(T x, T y) {
  return x - y * floor(x, y);
}
template <typename T>
pair<T, T> divmod(T x, T y) {
  T q = floor(x, y);
  return {q, x - q * y};
}

template <typename T, typename U>
T SUM(const vector<U> &A) {
  T sm = 0;
  for (auto &&a: A) sm += a;
  return sm;
}

#define MIN(v) *min_element(all(v))
#define MAX(v) *max_element(all(v))
#define LB(c, x) distance((c).begin(), lower_bound(all(c), (x)))
#define UB(c, x) distance((c).begin(), upper_bound(all(c), (x)))
#define UNIQUE(x) sort(all(x)), x.erase(unique(all(x)), x.end()), x.shrink_to_fit()

template <typename T>
T POP(deque<T> &que) {
  T a = que.front();
  que.pop_front();
  return a;
}
template <typename T>
T POP(pq<T> &que) {
  T a = que.top();
  que.pop();
  return a;
}
template <typename T>
T POP(pqg<T> &que) {
  T a = que.top();
  que.pop();
  return a;
}
template <typename T>
T POP(vc<T> &que) {
  T a = que.back();
  que.pop_back();
  return a;
}

template <typename F>
ll binary_search(F check, ll ok, ll ng, bool check_ok = true) {
  if (check_ok) assert(check(ok));
  while (abs(ok - ng) > 1) {
    auto x = (ng + ok) / 2;
    (check(x) ? ok : ng) = x;
  }
  return ok;
}
template <typename F>
double binary_search_real(F check, double ok, double ng, int iter = 100) {
  FOR(iter) {
    double x = (ok + ng) / 2;
    (check(x) ? ok : ng) = x;
  }
  return (ok + ng) / 2;
}

template <class T, class S>
inline bool chmax(T &a, const S &b) {
  return (a < b ? a = b, 1 : 0);
}
template <class T, class S>
inline bool chmin(T &a, const S &b) {
  return (a > b ? a = b, 1 : 0);
}

// ? は -1
vc<int> s_to_vi(const string &S, char first_char) {
  vc<int> A(S.size());
  FOR(i, S.size()) { A[i] = (S[i] != '?' ? S[i] - first_char : -1); }
  return A;
}

template <typename T, typename U>
vector<T> cumsum(vector<U> &A, int off = 1) {
  int N = A.size();
  vector<T> B(N + 1);
  FOR(i, N) { B[i + 1] = B[i] + A[i]; }
  if (off == 0) B.erase(B.begin());
  return B;
}

// stable sort
template <typename T>
vector<int> argsort(const vector<T> &A) {
  vector<int> ids(len(A));
  iota(all(ids), 0);
  sort(all(ids), [&](int i, int j) { return (A[i] == A[j] ? i < j : A[i] < A[j]); });
  return ids;
}

// A[I[0]], A[I[1]], ...
template <typename T>
vc<T> rearrange(const vc<T> &A, const vc<int> &I) {
  vc<T> B(len(I));
  FOR(i, len(I)) B[i] = A[I[i]];
  return B;
}

template <typename T, typename... Vectors>
void concat(vc<T> &first, const Vectors &... others) {
  vc<T> &res = first;
  (res.insert(res.end(), others.begin(), others.end()), ...);
}
#endif
#line 1 "other/io.hpp"
#define FASTIO
#include <unistd.h>


// https://judge.yosupo.jp/submission/21623

namespace fastio {
static constexpr uint32_t SZ = 1 << 17;
char ibuf[SZ];
char obuf[SZ];
char out[100];
// pointer of ibuf, obuf

uint32_t pil = 0, pir = 0, por = 0;

struct Pre {
  char num[10000][4];
  constexpr Pre() : num() {
    for (int i = 0; i < 10000; i++) {
      int n = i;
      for (int j = 3; j >= 0; j--) {
        num[i][j] = n % 10 | '0';
        n /= 10;
      }
    }
  }
} constexpr pre;

inline void load() {
  memcpy(ibuf, ibuf + pil, pir - pil);
  pir = pir - pil + fread(ibuf + pir - pil, 1, SZ - pir + pil, stdin);
  pil = 0;
  if (pir < SZ) ibuf[pir++] = '\n';
}

inline void flush() {
  fwrite(obuf, 1, por, stdout);
  por = 0;
}

void rd(char &c) {
  do {
    if (pil + 1 > pir) load();
    c = ibuf[pil++];
  } while (isspace(c));
}

void rd(string &x) {
  x.clear();
  char c;
  do {
    if (pil + 1 > pir) load();
    c = ibuf[pil++];
  } while (isspace(c));
  do {
    x += c;
    if (pil == pir) load();
    c = ibuf[pil++];
  } while (!isspace(c));
}

template <typename T>
void rd_real(T &x) {
  string s;
  rd(s);
  x = stod(s);
}

template <typename T>
void rd_integer(T &x) {
  if (pil + 100 > pir) load();
  char c;
  do
    c = ibuf[pil++];
  while (c < '-');
  bool minus = 0;
  if constexpr (is_signed<T>::value || is_same_v<T, i128>) {
    if (c == '-') { minus = 1, c = ibuf[pil++]; }
  }
  x = 0;
  while ('0' <= c) { x = x * 10 + (c & 15), c = ibuf[pil++]; }
  if constexpr (is_signed<T>::value || is_same_v<T, i128>) {
    if (minus) x = -x;
  }
}

void rd(int &x) { rd_integer(x); }
void rd(ll &x) { rd_integer(x); }
void rd(i128 &x) { rd_integer(x); }
void rd(u32 &x) { rd_integer(x); }
void rd(u64 &x) { rd_integer(x); }
void rd(u128 &x) { rd_integer(x); }
void rd(double &x) { rd_real(x); }
void rd(long double &x) { rd_real(x); }
void rd(f128 &x) { rd_real(x); }

template <class T, class U>
void rd(pair<T, U> &p) {
  return rd(p.first), rd(p.second);
}
template <size_t N = 0, typename T>
void rd_tuple(T &t) {
  if constexpr (N < std::tuple_size<T>::value) {
    auto &x = std::get<N>(t);
    rd(x);
    rd_tuple<N + 1>(t);
  }
}
template <class... T>
void rd(tuple<T...> &tpl) {
  rd_tuple(tpl);
}

template <size_t N = 0, typename T>
void rd(array<T, N> &x) {
  for (auto &d: x) rd(d);
}
template <class T>
void rd(vc<T> &x) {
  for (auto &d: x) rd(d);
}

void read() {}
template <class H, class... T>
void read(H &h, T &... t) {
  rd(h), read(t...);
}

void wt(const char c) {
  if (por == SZ) flush();
  obuf[por++] = c;
}
void wt(const string s) {
  for (char c: s) wt(c);
}
void wt(const char *s) {
  size_t len = strlen(s);
  for (size_t i = 0; i < len; i++) wt(s[i]);
}

template <typename T>
void wt_integer(T x) {
  if (por > SZ - 100) flush();
  if (x < 0) { obuf[por++] = '-', x = -x; }
  int outi;
  for (outi = 96; x >= 10000; outi -= 4) {
    memcpy(out + outi, pre.num[x % 10000], 4);
    x /= 10000;
  }
  if (x >= 1000) {
    memcpy(obuf + por, pre.num[x], 4);
    por += 4;
  } else if (x >= 100) {
    memcpy(obuf + por, pre.num[x] + 1, 3);
    por += 3;
  } else if (x >= 10) {
    int q = (x * 103) >> 10;
    obuf[por] = q | '0';
    obuf[por + 1] = (x - q * 10) | '0';
    por += 2;
  } else
    obuf[por++] = x | '0';
  memcpy(obuf + por, out + outi + 4, 96 - outi);
  por += 96 - outi;
}

template <typename T>
void wt_real(T x) {
  ostringstream oss;
  oss << fixed << setprecision(15) << double(x);
  string s = oss.str();
  wt(s);
}

void wt(int x) { wt_integer(x); }
void wt(ll x) { wt_integer(x); }
void wt(i128 x) { wt_integer(x); }
void wt(u32 x) { wt_integer(x); }
void wt(u64 x) { wt_integer(x); }
void wt(u128 x) { wt_integer(x); }
void wt(double x) { wt_real(x); }
void wt(long double x) { wt_real(x); }
void wt(f128 x) { wt_real(x); }

template <class T, class U>
void wt(const pair<T, U> val) {
  wt(val.first);
  wt(' ');
  wt(val.second);
}
template <size_t N = 0, typename T>
void wt_tuple(const T t) {
  if constexpr (N < std::tuple_size<T>::value) {
    if constexpr (N > 0) { wt(' '); }
    const auto x = std::get<N>(t);
    wt(x);
    wt_tuple<N + 1>(t);
  }
}
template <class... T>
void wt(tuple<T...> tpl) {
  wt_tuple(tpl);
}
template <class T, size_t S>
void wt(const array<T, S> val) {
  auto n = val.size();
  for (size_t i = 0; i < n; i++) {
    if (i) wt(' ');
    wt(val[i]);
  }
}
template <class T>
void wt(const vector<T> val) {
  auto n = val.size();
  for (size_t i = 0; i < n; i++) {
    if (i) wt(' ');
    wt(val[i]);
  }
}

void print() { wt('\n'); }
template <class Head, class... Tail>
void print(Head &&head, Tail &&... tail) {
  wt(head);
  if (sizeof...(Tail)) wt(' ');
  print(forward<Tail>(tail)...);
}

// gcc expansion. called automaticall after main.

void __attribute__((destructor)) _d() { flush(); }
} // namespace fastio

using fastio::read;
using fastio::print;
using fastio::flush;

#if defined(LOCAL)
#define SHOW(...) SHOW_IMPL(__VA_ARGS__, SHOW6, SHOW5, SHOW4, SHOW3, SHOW2, SHOW1)(__VA_ARGS__)
#define SHOW_IMPL(_1, _2, _3, _4, _5, _6, NAME, ...) NAME
#define SHOW1(x) print(#x, "=", (x)), flush()
#define SHOW2(x, y) print(#x, "=", (x), #y, "=", (y)), flush()
#define SHOW3(x, y, z) print(#x, "=", (x), #y, "=", (y), #z, "=", (z)), flush()
#define SHOW4(x, y, z, w) print(#x, "=", (x), #y, "=", (y), #z, "=", (z), #w, "=", (w)), flush()
#define SHOW5(x, y, z, w, v) print(#x, "=", (x), #y, "=", (y), #z, "=", (z), #w, "=", (w), #v, "=", (v)), flush()
#define SHOW6(x, y, z, w, v, u) print(#x, "=", (x), #y, "=", (y), #z, "=", (z), #w, "=", (w), #v, "=", (v), #u, "=", (u)), flush()
#else
#define SHOW(...)
#endif

#define INT(...)   \
  int __VA_ARGS__; \
  read(__VA_ARGS__)
#define LL(...)   \
  ll __VA_ARGS__; \
  read(__VA_ARGS__)
#define U32(...)   \
  u32 __VA_ARGS__; \
  read(__VA_ARGS__)
#define U64(...)   \
  u64 __VA_ARGS__; \
  read(__VA_ARGS__)
#define STR(...)      \
  string __VA_ARGS__; \
  read(__VA_ARGS__)
#define CHAR(...)   \
  char __VA_ARGS__; \
  read(__VA_ARGS__)
#define DBL(...)      \
  double __VA_ARGS__; \
  read(__VA_ARGS__)

#define VEC(type, name, size) \
  vector<type> name(size);    \
  read(name)
#define VV(type, name, h, w)                     \
  vector<vector<type>> name(h, vector<type>(w)); \
  read(name)

void YES(bool t = 1) { print(t ? "YES" : "NO"); }
void NO(bool t = 1) { YES(!t); }
void Yes(bool t = 1) { print(t ? "Yes" : "No"); }
void No(bool t = 1) { Yes(!t); }
void yes(bool t = 1) { print(t ? "yes" : "no"); }
void no(bool t = 1) { yes(!t); }
void YA(bool t = 1) { print(t ? "YA" : "TIDAK"); }
void TIDAK(bool t = 1) { YES(!t); }
#line 2 "alg/monoid/add.hpp"

template <typename E>
struct Monoid_Add {
  using X = E;
  using value_type = X;
  static constexpr X op(const X &x, const X &y) noexcept { return x + y; }
  static constexpr X inverse(const X &x) noexcept { return -x; }
  static constexpr X power(const X &x, ll n) noexcept { return X(n) * x; }
  static constexpr X unit() { return X(0); }
  static constexpr bool commute = true;
};
#line 2 "alg/monoid/max.hpp"

template <typename E>
struct Monoid_Max {
  using X = E;
  using value_type = X;
  static constexpr X op(const X &x, const X &y) noexcept { return max(x, y); }
  static constexpr X unit() { return -infty<E>; }
  static constexpr bool commute = true;
};
#line 3 "alg/acted_monoid/max_add.hpp"

template <typename E>
struct ActedMonoid_Max_Add {
  using Monoid_X = Monoid_Max<E>;
  using Monoid_A = Monoid_Add<E>;
  using X = typename Monoid_X::value_type;
  using A = typename Monoid_A::value_type;
  static constexpr X act(const X &x, const A &a, const ll &size) {
    if (x == -infty<E>) return x;
    return x + a;
  }
};
#line 1 "ds/randomized_bst/rbst_acted_monoid.hpp"
template <typename ActedMonoid, bool PERSISTENT>
struct RBST_ActedMonoid {
  using Monoid_X = typename ActedMonoid::Monoid_X;
  using Monoid_A = typename ActedMonoid::Monoid_A;
  using X = typename Monoid_X::value_type;
  using A = typename Monoid_A::value_type;

  struct Node {
    Node *l, *r;
    X x, prod; // lazy, rev 反映済
    A lazy;
    u32 size;
    bool rev;
  };

  Node *pool;
  const int NODES;
  int pid;
  using np = Node *;

  RBST_ActedMonoid(int NODES) : NODES(NODES), pid(0) { pool = new Node[NODES]; }
  ~RBST_ActedMonoid() { delete[] pool; }

  void reset() { pid = 0; }

  np new_node(const X &x) {
    pool[pid].l = pool[pid].r = nullptr;
    pool[pid].x = x;
    pool[pid].prod = x;
    pool[pid].lazy = Monoid_A::unit();
    pool[pid].size = 1;
    pool[pid].rev = 0;
    return &(pool[pid++]);
  }

  np new_node(const vc<X> &dat) {
    auto dfs = [&](auto &dfs, u32 l, u32 r) -> np {
      if (l == r) return nullptr;
      if (r == l + 1) return new_node(dat[l]);
      u32 m = (l + r) / 2;
      np l_root = dfs(dfs, l, m);
      np r_root = dfs(dfs, m + 1, r);
      np root = new_node(dat[m]);
      root->l = l_root, root->r = r_root;
      update(root);
      return root;
    };
    return dfs(dfs, 0, len(dat));
  }

  np copy_node(np &n) {
    if (!n || !PERSISTENT) return n;
    pool[pid].l = n->l, pool[pid].r = n->r;
    pool[pid].x = n->x;
    pool[pid].prod = n->prod;
    pool[pid].lazy = n->lazy;
    pool[pid].size = n->size;
    pool[pid].rev = n->rev;
    return &(pool[pid++]);
  }

  np merge(np l_root, np r_root) { return merge_rec(l_root, r_root); }
  np merge3(np a, np b, np c) { return merge(merge(a, b), c); }
  np merge4(np a, np b, np c, np d) { return merge(merge(merge(a, b), c), d); }
  pair<np, np> split(np root, u32 k) {
    if (!root) {
      assert(k == 0);
      return {nullptr, nullptr};
    }
    assert(0 <= k && k <= root->size);
    return split_rec(root, k);
  }
  tuple<np, np, np> split3(np root, u32 l, u32 r) {
    np nm, nr;
    tie(root, nr) = split(root, r);
    tie(root, nm) = split(root, l);
    return {root, nm, nr};
  }
  tuple<np, np, np, np> split4(np root, u32 i, u32 j, u32 k) {
    np d;
    tie(root, d) = split(root, k);
    auto [a, b, c] = split3(root, i, j);
    return {a, b, c, d};
  }

  X prod(np root, u32 l, u32 r) {
    if (l == r) return Monoid_X::unit();
    return prod_rec(root, l, r, false);
  }
  X prod(np root) { return (root ? root->prod : Monoid_X::unit()); }

  np reverse(np root, u32 l, u32 r) {
    assert(Monoid_X::commute);
    assert(0 <= l && l <= r && r <= root->size);
    if (r - l <= 1) return root;
    auto [nl, nm, nr] = split3(root, l, r);
    nm->rev ^= 1;
    swap(nm->l, nm->r);
    return merge3(nl, nm, nr);
  }

  np apply(np root, u32 l, u32 r, const A a) {
    assert(0 <= l && l <= r && r <= root->size);
    return apply_rec(root, l, r, a);
  }
  np apply(np root, const A a) {
    if (!root) return root;
    return apply_rec(root, 0, root->size, a);
  }

  np set(np root, u32 k, const X &x) { return set_rec(root, k, x); }
  np multiply(np root, u32 k, const X &x) { return multiply_rec(root, k, x); }
  X get(np root, u32 k) { return get_rec(root, k, false, Monoid_A::unit()); }

  vc<X> get_all(np root) {
    vc<X> res;
    auto dfs = [&](auto &dfs, np root, bool rev, A lazy) -> void {
      if (!root) return;
      X me = ActedMonoid::act(root->x, lazy, 1);
      lazy = Monoid_A::op(root->lazy, lazy);
      dfs(dfs, (rev ? root->r : root->l), rev ^ root->rev, lazy);
      res.eb(me);
      dfs(dfs, (rev ? root->l : root->r), rev ^ root->rev, lazy);
    };
    dfs(dfs, root, 0, Monoid_A::unit());
    return res;
  }

  template <typename F>
  pair<np, np> split_max_right(np root, const F check) {
    assert(check(Monoid_X::unit()));
    X x = Monoid_X::unit();
    return split_max_right_rec(root, check, x);
  }

private:
  inline u32 xor128() {
    static u32 x = 123456789;
    static u32 y = 362436069;
    static u32 z = 521288629;
    static u32 w = 88675123;
    u32 t = x ^ (x << 11);
    x = y;
    y = z;
    z = w;
    return w = (w ^ (w >> 19)) ^ (t ^ (t >> 8));
  }

  void prop(np c) {
    // 自身をコピーする必要はない。
    // 子をコピーする必要がある。複数の親を持つ可能性があるため。
    bool bl_lazy = (c->lazy != Monoid_A::unit());
    bool bl_rev = c->rev;
    if (bl_lazy || bl_rev) {
      c->l = copy_node(c->l);
      c->r = copy_node(c->r);
    }
    if (c->lazy != Monoid_A::unit()) {
      if (c->l) {
        c->l->x = ActedMonoid::act(c->l->x, c->lazy, 1);
        c->l->prod = ActedMonoid::act(c->l->prod, c->lazy, c->l->size);
        c->l->lazy = Monoid_A::op(c->l->lazy, c->lazy);
      }
      if (c->r) {
        c->r->x = ActedMonoid::act(c->r->x, c->lazy, 1);
        c->r->prod = ActedMonoid::act(c->r->prod, c->lazy, c->r->size);
        c->r->lazy = Monoid_A::op(c->r->lazy, c->lazy);
      }
      c->lazy = Monoid_A::unit();
    }
    if (c->rev) {
      if (c->l) {
        c->l->rev ^= 1;
        swap(c->l->l, c->l->r);
      }
      if (c->r) {
        c->r->rev ^= 1;
        swap(c->r->l, c->r->r);
      }
      c->rev = 0;
    }
  }

  void update(np c) {
    // データを保ったまま正常化するだけなので、コピー不要
    c->size = 1;
    c->prod = c->x;
    if (c->l) {
      c->size += c->l->size;
      c->prod = Monoid_X::op(c->l->prod, c->prod);
    }
    if (c->r) {
      c->size += c->r->size;
      c->prod = Monoid_X::op(c->prod, c->r->prod);
    }
  }

  np merge_rec(np l_root, np r_root) {
    if (!l_root) return r_root;
    if (!r_root) return l_root;
    u32 sl = l_root->size, sr = r_root->size;
    if (xor128() % (sl + sr) < sl) {
      prop(l_root);
      l_root = copy_node(l_root);
      l_root->r = merge_rec(l_root->r, r_root);
      update(l_root);
      return l_root;
    }
    prop(r_root);
    r_root = copy_node(r_root);
    r_root->l = merge_rec(l_root, r_root->l);
    update(r_root);
    return r_root;
  }

  pair<np, np> split_rec(np root, u32 k) {
    if (!root) return {nullptr, nullptr};
    prop(root);
    u32 sl = (root->l ? root->l->size : 0);
    if (k <= sl) {
      auto [nl, nr] = split_rec(root->l, k);
      root = copy_node(root);
      root->l = nr;
      update(root);
      return {nl, root};
    }
    auto [nl, nr] = split_rec(root->r, k - (1 + sl));
    root = copy_node(root);
    root->r = nl;
    update(root);
    return {root, nr};
  }

  np set_rec(np root, u32 k, const X &x) {
    if (!root) return root;
    prop(root);
    u32 sl = (root->l ? root->l->size : 0);
    if (k < sl) {
      root = copy_node(root);
      root->l = set_rec(root->l, k, x);
      update(root);
      return root;
    }
    if (k == sl) {
      root = copy_node(root);
      root->x = x;
      update(root);
      return root;
    }
    root = copy_node(root);
    root->r = set_rec(root->r, k - (1 + sl), x);
    update(root);
    return root;
  }

  np multiply_rec(np root, u32 k, const X &x) {
    if (!root) return root;
    prop(root);
    u32 sl = (root->l ? root->l->size : 0);
    if (k < sl) {
      root = copy_node(root);
      root->l = multiply_rec(root->l, k, x);
      update(root);
      return root;
    }
    if (k == sl) {
      root = copy_node(root);
      root->x = Monoid_X::op(root->x, x);
      update(root);
      return root;
    }
    root = copy_node(root);
    root->r = multiply_rec(root->r, k - (1 + sl), x);
    update(root);
    return root;
  }

  X prod_rec(np root, u32 l, u32 r, bool rev) {
    if (l == 0 && r == root->size) { return root->prod; }
    np left = (rev ? root->r : root->l);
    np right = (rev ? root->l : root->r);
    u32 sl = (left ? left->size : 0);
    X res = Monoid_X::unit();
    if (l < sl) {
      X y = prod_rec(left, l, min(r, sl), rev ^ root->rev);
      res = Monoid_X::op(res, ActedMonoid::act(y, root->lazy, min(r, sl) - l));
    }
    if (l <= sl && sl < r) res = Monoid_X::op(res, root->x);
    u32 k = 1 + sl;
    if (k < r) {
      X y = prod_rec(right, max(k, l) - k, r - k, rev ^ root->rev);
      res = Monoid_X::op(res, ActedMonoid::act(y, root->lazy, r - max(k, l)));
    }
    return res;
  }

  X get_rec(np root, u32 k, bool rev, A lazy) {
    np left = (rev ? root->r : root->l);
    np right = (rev ? root->l : root->r);
    u32 sl = (left ? left->size : 0);
    if (k == sl) return ActedMonoid::act(root->x, lazy, 1);
    lazy = Monoid_A::op(root->lazy, lazy);
    rev ^= root->rev;
    if (k < sl) return get_rec(left, k, rev, lazy);
    return get_rec(right, k - (1 + sl), rev, lazy);
  }

  np apply_rec(np root, u32 l, u32 r, const A &a) {
    prop(root);
    root = copy_node(root);
    if (l == 0 && r == root->size) {
      root->x = ActedMonoid::act(root->x, a, 1);
      root->prod = ActedMonoid::act(root->prod, a, root->size);
      root->lazy = a;
      return root;
    }
    u32 sl = (root->l ? root->l->size : 0);
    if (l < sl) root->l = apply_rec(root->l, l, min(r, sl), a);
    if (l <= sl && sl < r) root->x = ActedMonoid::act(root->x, a, 1);
    u32 k = 1 + sl;
    if (k < r) root->r = apply_rec(root->r, max(k, l) - k, r - k, a);
    update(root);
    return root;
  }

  template <typename F>
  pair<np, np> split_max_right_rec(np root, F check, X &x) {
    if (!root) return {nullptr, nullptr};
    prop(root);
    root = copy_node(root);
    X y = Monoid_X::op(x, root->prod);
    if (check(y)) {
      x = y;
      return {root, nullptr};
    }
    np left = root->l, right = root->r;
    if (left) {
      X y = Monoid_X::op(x, root->l->prod);
      if (!check(y)) {
        auto [n1, n2] = split_max_right_rec(left, check, x);
        root->l = n2;
        update(root);
        return {n1, root};
      }
      x = y;
    }
    y = Monoid_X::op(x, root->x);
    if (!check(y)) {
      root->l = nullptr;
      update(root);
      return {left, root};
    }
    x = y;
    auto [n1, n2] = split_max_right_rec(right, check, x);
    root->r = n1;
    update(root);
    return {root, n2};
  }
};
#line 6 "test/3_yukicoder/686.test.cpp"

void solve() {
  LL(N);
  using AM = ActedMonoid_Max_Add<int>;
  RBST_ActedMonoid<AM, false> X(1 + N);
  using np = decltype(X)::np;

  np root = X.new_node(infty<int>);

  FOR(N) {
    if (X.prod(root) != infty<int>) root = X.merge(root, X.new_node(infty<int>));
    LL(L, R);
    // L未満 / R 未満
    np a, b, c, c1, c2;
    auto check_L = [&](int e) -> bool { return e < L; };
    auto check_R = [&](int e) -> bool { return e < R; };
    tie(a, root) = X.split_max_right(root, check_L);
    tie(b, c) = X.split_max_right(root, check_R);
    tie(c1, c2) = X.split(c, 1);
    b = X.apply(b, 1);
    c1 = X.set(c1, 0, L);
    root = X.merge4(a, c1, b, c2);
  }
  auto check = [&](int e) -> bool { return e < infty<int>; };
  auto [n1, n2] = X.split_max_right(root, check);
  int ANS = (n1 ? n1->size : 0);
  print(ANS);
}

signed main() {
  solve();
  return 0;
}
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