library

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:heavy_check_mark: test/5_atcoder/abc285g.test.cpp

Depends on

Code

#define PROBLEM "https://atcoder.jp/contests/abc285/tasks/abc285_g"
#include "my_template.hpp"
#include "other/io.hpp"

#include "flow/maxflow_with_lowerbound.hpp"

void solve() {
  INT(H, W);
  auto idx = [&](int x, int y) -> int { return W * x + y; };
  int s = idx(H, 0);
  int t = s + 1;
  MaxFlow_With_LowerBound<int> G(t + 1, s, t);
  VEC(string, A, H);
  auto isin = [&](int x, int y) -> bool { return (0 <= x && x < H && 0 <= y && y < W); };
  int dx[] = {1, 0, -1, 0, 1, 1, -1, -1};
  int dy[] = {0, 1, 0, -1, 1, -1, 1, -1};
  FOR(i, H) FOR(j, W) {
    if (A[i][j] == '2') {
      if ((i + j) % 2 == 0) G.add(s, idx(i, j), 1, 1);
      if ((i + j) % 2 == 1) G.add(idx(i, j), t, 1, 1);
    }
    elif (A[i][j] == '?') {
      if ((i + j) % 2 == 0) G.add(s, idx(i, j), 0, 1);
      if ((i + j) % 2 == 1) G.add(idx(i, j), t, 0, 1);
    }
    if ((i + j) % 2 == 0) {
      FOR(d, 4) {
        int ni = i + dx[d], nj = j + dy[d];
        if (!isin(ni, nj)) continue;
        G.add(idx(i, j), idx(ni, nj), 0, 1);
      }
    }
  }
  int F = G.flow();
  Yes(F != -1);
}

signed main() {
  int T = 1;
  // INT(T);
  FOR(T) solve();
  return 0;
}
#line 1 "test/5_atcoder/abc285g.test.cpp"
#define PROBLEM "https://atcoder.jp/contests/abc285/tasks/abc285_g"
#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 u32 = unsigned int;
using u64 = unsigned long long;
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 FOR_subset(t, s) for (ll t = (s); t >= 0; t = (t == 0 ? -1 : (t - 1) & (s)))
#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_mod_2(int x) { return __builtin_parity(x); }
int popcnt_mod_2(u32 x) { return __builtin_parity(x); }
int popcnt_mod_2(ll x) { return __builtin_parityll(x); }
int popcnt_mod_2(u64 x) { return __builtin_parityll(x); }
// (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 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); }
#line 4 "test/5_atcoder/abc285g.test.cpp"

#line 1 "flow/maxflow_with_lowerbound.hpp"

template <typename Cap>
struct MaxFlow_With_LowerBound {
  int N, s, t, S, T;
  Cap flow_ans;
  bool prepared = 0;

  struct Edge_raw {
    int frm, to;
    Cap lo, hi;
    Edge_raw(int frm, int to, Cap lo, Cap hi) : frm(frm), to(to), lo(lo), hi(hi){};
  };
  vc<Edge_raw> dat;

  MaxFlow_With_LowerBound(int N, int s, int t) : N(N), s(s), t(t), S(N), T(N + 1), flow_ans(0) {
    assert(0 <= s && s < N);
    assert(0 <= t && t < N);
  }
  void add(int frm, int to, Cap lo, Cap hi) {
    assert(!prepared);
    assert(0 <= frm && frm < N);
    assert(0 <= to && to < N);
    assert(Cap(0) <= lo && lo <= hi);
    dat.eb(Edge_raw(frm, to, lo, hi));
  }

  struct Edge {
    int rev, to;
    Cap cap, flow;
  };

  vc<Edge> G;
  vc<int> indptr;
  vc<int> idx;
  vc<int> level, que, prog;

  void debug() {
    print("frm,to,lo,hi");
    for (auto& e: dat) print(e.frm, e.to, e.lo, e.hi);
  }

  void build() {
    assert(!prepared);
    prepared = 1;
    int M = len(dat);
    idx.assign(6 * M, -1);
    vc<int> cnt(N + 2);
    FOR(i, M) {
      auto [frm, to, lo, hi] = dat[i];
      if (frm == to) continue;
      if (lo < hi) cnt[frm]++, cnt[to]++;
      if (0 < lo) cnt[S]++, cnt[to]++, cnt[frm]++, cnt[T]++;
    }
    indptr = cumsum<int>(cnt);
    int m = indptr.back();
    G.resize(m);
    vc<int> prog = indptr;
    auto add = [&](int i, int j, int a, int b, Cap c) -> void {
      int p = prog[a]++, q = prog[b]++;
      idx[i] = p, idx[j] = q;
      G[p] = {q, b, c, 0};
      G[q] = {p, a, 0, 0};
    };
    FOR(i, M) {
      auto [frm, to, lo, hi] = dat[i];
      if (frm == to) continue;
      if (lo < hi) add(6 * i + 0, 6 * i + 1, frm, to, hi - lo);
      if (0 < lo) {
        add(6 * i + 2, 6 * i + 3, S, to, lo);
        add(6 * i + 4, 6 * i + 5, frm, T, lo);
        cnt[S]++, cnt[to]++, cnt[frm]++, cnt[T]++;
      }
    }
  }

  Cap flow() {
    build();
    Cap a = flow_st(S, T), b = flow_st(S, t), c = flow_st(s, T), d = flow_st(s, t);
    bool valid = 1;
    int M = len(dat);
    FOR(i, M) {
      auto [frm, to, lo, hi] = dat[i];
      if (lo > 0 && G[idx[6 * i + 2]].cap > 0) valid = 0;
      if (lo > 0 && G[idx[6 * i + 4]].cap > 0) valid = 0;
    }
    if (!valid) return flow_ans = -1;
    assert(a + b == a + c && c + d == b + d);
    return flow_ans = c + d;
  }

  void set_level(int s) {
    level.assign(N + 2, infty<int>);
    que.resize(N + 2);
    int ql = 0, qr = 0;
    auto upd = [&](int v, int d) -> void {
      if (chmin(level[v], d)) que[qr++] = v;
    };
    upd(s, 0);
    while (ql < qr) {
      int v = que[ql++];
      FOR(i, indptr[v], indptr[v + 1]) {
        auto& e = G[i];
        if (e.cap > 0) upd(e.to, level[v] + 1);
      }
    }
  }

  Cap flow_dfs(int s, int t) {
    prog = indptr;
    auto dfs = [&](auto& dfs, int v, Cap lim) -> Cap {
      if (v == t) return lim;
      Cap res = 0;
      for (int& i = prog[v]; i < indptr[v + 1]; ++i) {
        auto& e = G[i];
        if (e.cap > 0 && level[e.to] == level[v] + 1) {
          Cap a = dfs(dfs, e.to, min(lim, e.cap));
          if (a == Cap(0)) continue;
          e.cap -= a, e.flow += a;
          G[e.rev].cap += a, G[e.rev].flow -= a;
          res += a, lim -= a;
          if (lim == Cap(0)) break;
        }
      }
      return res;
    };
    return dfs(dfs, s, infty<Cap>);
  }

  Cap flow_st(int s, int t) {
    Cap ans = 0;
    while (1) {
      set_level(s);
      if (level[t] == infty<int>) break;
      ans += flow_dfs(s, t);
    }
    return ans;
  }

  // add した順にひととおり
  vc<Cap> get_flow_result() {
    assert(flow_ans != Cap(-1));
    int M = len(dat);
    vc<Cap> res(M);
    FOR(i, M) {
      auto [frm, to, lo, hi] = dat[i];
      Cap flow = (lo < hi ? G[idx[6 * i + 1]].cap + lo : lo);
      // print(frm, to, lo, hi, flow);
      res[i] = flow;
    }
    return res;
  }
};
#line 6 "test/5_atcoder/abc285g.test.cpp"

void solve() {
  INT(H, W);
  auto idx = [&](int x, int y) -> int { return W * x + y; };
  int s = idx(H, 0);
  int t = s + 1;
  MaxFlow_With_LowerBound<int> G(t + 1, s, t);
  VEC(string, A, H);
  auto isin = [&](int x, int y) -> bool { return (0 <= x && x < H && 0 <= y && y < W); };
  int dx[] = {1, 0, -1, 0, 1, 1, -1, -1};
  int dy[] = {0, 1, 0, -1, 1, -1, 1, -1};
  FOR(i, H) FOR(j, W) {
    if (A[i][j] == '2') {
      if ((i + j) % 2 == 0) G.add(s, idx(i, j), 1, 1);
      if ((i + j) % 2 == 1) G.add(idx(i, j), t, 1, 1);
    }
    elif (A[i][j] == '?') {
      if ((i + j) % 2 == 0) G.add(s, idx(i, j), 0, 1);
      if ((i + j) % 2 == 1) G.add(idx(i, j), t, 0, 1);
    }
    if ((i + j) % 2 == 0) {
      FOR(d, 4) {
        int ni = i + dx[d], nj = j + dy[d];
        if (!isin(ni, nj)) continue;
        G.add(idx(i, j), idx(ni, nj), 0, 1);
      }
    }
  }
  int F = G.flow();
  Yes(F != -1);
}

signed main() {
  int T = 1;
  // INT(T);
  FOR(T) solve();
  return 0;
}
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