Problem p03263 (C++)

Buggy submission (status: Runtime Error):
#include <bits/stdc++.h>
// created [2020/02/02] 21:33:37
#pragma GCC diagnostic ignored "-Wsign-compare"
#pragma GCC diagnostic ignored "-Wsign-conversion"

using i32 = int32_t;
using i64 = int64_t;
using u32 = uint32_t;
using u64 = uint64_t;
using uint = unsigned int;
using usize = std::size_t;
using ll = long long;
using ull = unsigned long long;
using ld = long double;
template <typename T, usize n> using arr = T (&)[n];
template <typename T, usize n> using c_arr = const T (&)[n];
template <typename T> using max_heap = std::priority_queue<T>;
template <typename T>
using min_heap = std::priority_queue<T, std::vector<T>, std::greater<T>>;
template <typename T> constexpr T popcount(const T u) {
  return u ? static_cast<T>(__builtin_popcountll(static_cast<u64>(u)))
           : static_cast<T>(0);
}
template <typename T> constexpr T log2p1(const T u) {
  return u ? static_cast<T>(64 - __builtin_clzll(static_cast<u64>(u)))
           : static_cast<T>(0);
}
template <typename T> constexpr T msbp1(const T u) { return log2p1(u); }
template <typename T> constexpr T lsbp1(const T u) {
  return __builtin_ffsll(u);
}
template <typename T> constexpr T clog(const T u) {
  return u ? log2p1(u - 1) : static_cast<T>(u);
}
template <typename T> constexpr bool ispow2(const T u) {
  return u and (static_cast<u64>(u) & static_cast<u64>(u - 1)) == 0;
}
template <typename T> constexpr T ceil2(const T u) {
  return static_cast<T>(1) << clog(u);
}
template <typename T> constexpr T floor2(const T u) {
  return u == 0 ? static_cast<T>(0) : static_cast<T>(1) << (log2p1(u) - 1);
}
template <typename T> constexpr bool btest(const T mask, const usize ind) {
  return static_cast<bool>((static_cast<u64>(mask) >> ind) &
                           static_cast<u64>(1));
}
template <typename T> void bset(T &mask, const usize ind) {
  mask |= (static_cast<T>(1) << ind);
}
template <typename T> void breset(T &mask, const usize ind) {
  mask &= ~(static_cast<T>(1) << ind);
}
template <typename T> void bflip(T &mask, const usize ind) {
  mask ^= (static_cast<T>(1) << ind);
}
template <typename T> void bset(T &mask, const usize ind, const bool b) {
  (b ? bset(mask, ind) : breset(mask, ind));
}
template <typename T> constexpr T bcut(const T mask, const usize ind) {
  return ind == 0 ? static_cast<T>(0)
                  : static_cast<T>((static_cast<u64>(mask) << (64 - ind)) >>
                                   (64 - ind));
}
template <typename T> bool chmin(T &a, const T &b) {
  return (a > b ? a = b, true : false);
}
template <typename T> bool chmax(T &a, const T &b) {
  return (a < b ? a = b, true : false);
}
constexpr unsigned int mod = 1000000007;
template <typename T> constexpr T inf_v = std::numeric_limits<T>::max() / 4;
template <typename Real>
constexpr Real pi_v = Real{3.141592653589793238462643383279502884};
auto mfp = [](auto &&f) {
  return [=](auto &&...args) {
    return f(f, std::forward<decltype(args)>(args)...);
  };
};

template <typename T> T in() {
  T v;
  return std::cin >> v, v;
}
template <typename T, typename Uint, usize n, usize i>
T in_v(typename std::enable_if<(i == n), c_arr<Uint, n>>::type) {
  return in<T>();
}
template <typename T, typename Uint, usize n, usize i>
auto in_v(typename std::enable_if<(i < n), c_arr<Uint, n>>::type &szs) {
  const usize s = (usize)szs[i];
  std::vector<decltype(in_v<T, Uint, n, i + 1>(szs))> ans(s);
  for (usize j = 0; j < s; j++) {
    ans[j] = in_v<T, Uint, n, i + 1>(szs);
  }
  return ans;
}
template <typename T, typename Uint, usize n> auto in_v(c_arr<Uint, n> szs) {
  return in_v<T, Uint, n, 0>(szs);
}
template <typename... Types> auto in_t() {
  return std::tuple<std::decay_t<Types>...>{in<Types>()...};
}
struct io_init {
  io_init() {
    std::cin.tie(nullptr), std::ios::sync_with_stdio(false);
    std::cout << std::fixed << std::setprecision(20);
  }
  void clear() { std::cin.tie(), std::ios::sync_with_stdio(true); }
} io_setting;

int out() { return 0; }
template <typename T> int out(const T &v) { return std::cout << v, 0; }
template <typename T> int out(const std::vector<T> &v) {
  for (usize i = 0; i < v.size(); i++) {
    if (i > 0) {
      std::cout << ' ';
    }
    out(v[i]);
  }
  return 0;
}
template <typename T1, typename T2> int out(const std::pair<T1, T2> &v) {
  return out(v.first), std::cout << ' ', out(v.second), 0;
}
template <typename T, typename... Args>
int out(const T &v, const Args... args) {
  return out(v), std::cout << ' ', out(args...), 0;
}
template <typename... Args> int outln(const Args... args) {
  return out(args...), std::cout << '\n', 0;
}
template <typename... Args> int outel(const Args... args) {
  return out(args...), std::cout << std::endl, 0;
}
#define SHOW(...) static_cast<void>(0)
constexpr ull TEN(const usize n) { return n == 0 ? 1ULL : TEN(n - 1) * 10ULL; }

template <typename T, typename Uint, usize n, usize i>
auto make_v(typename std::enable_if<(i == n), c_arr<Uint, n>>::type,
            const T &v = T{}) {
  return v;
}
template <typename T, typename Uint, usize n, usize i>
auto make_v(typename std::enable_if<(i < n), c_arr<Uint, n>>::type szs,
            const T &v = T{}) {
  const usize s = (usize)szs[i];
  return std::vector<decltype(make_v<T, Uint, n, i + 1>(szs, v))>(
      s, make_v<T, Uint, n, i + 1>(szs, v));
}
template <typename T, typename Uint, usize n>
auto make_v(c_arr<Uint, n> szs, const T &t = T{}) {
  return make_v<T, Uint, n, 0>(szs, t);
}
int main() {
  const auto H = in<int>(), W = in<int>();
  auto ass = in_v<int>({H, W});
  using pii = std::pair<int, int>;
  auto next = make_v<pii>({H, W});
  for (int i = 0; i < H; i++) {
    for (int j = 0; j < W; j++) {
      if (i % 2 == 0) {
        next[i][j] = (j == W - 1 ? pii{i + 1, j} : pii{i, j + 1});
      } else {
        next[i][j] = (j == 0 ? pii{i + 1, j} : pii{i, j - 1});
      }
    }
  }
  int y = 0, x = 0;
  std::vector<int> ys, xs, nys, nxs;
  while (y < H) {
    const auto nxt = next[y][x];
    const int ny = nxt.first, nx = nxt.second;
    if (ass[y][x] % 2 == 1) {
      ys.push_back(y + 1), xs.push_back(x + 1);
      nys.push_back(ny + 1), nxs.push_back(nx + 1);
      ass[y][x]--, ass[ny][nx]++;
    }
    y = ny, x = nx;
  }
  outln(ys.size());
  for (int i = 0; i < ys.size(); i++) {
    outln(ys[i], xs[i], nys[i], nxs[i]);
  }
  return 0;
}


Fixed submission:
#include <bits/stdc++.h>
// created [2020/02/02] 21:33:37
#pragma GCC diagnostic ignored "-Wsign-compare"
#pragma GCC diagnostic ignored "-Wsign-conversion"

using i32 = int32_t;
using i64 = int64_t;
using u32 = uint32_t;
using u64 = uint64_t;
using uint = unsigned int;
using usize = std::size_t;
using ll = long long;
using ull = unsigned long long;
using ld = long double;
template <typename T, usize n> using arr = T (&)[n];
template <typename T, usize n> using c_arr = const T (&)[n];
template <typename T> using max_heap = std::priority_queue<T>;
template <typename T>
using min_heap = std::priority_queue<T, std::vector<T>, std::greater<T>>;
template <typename T> constexpr T popcount(const T u) {
  return u ? static_cast<T>(__builtin_popcountll(static_cast<u64>(u)))
           : static_cast<T>(0);
}
template <typename T> constexpr T log2p1(const T u) {
  return u ? static_cast<T>(64 - __builtin_clzll(static_cast<u64>(u)))
           : static_cast<T>(0);
}
template <typename T> constexpr T msbp1(const T u) { return log2p1(u); }
template <typename T> constexpr T lsbp1(const T u) {
  return __builtin_ffsll(u);
}
template <typename T> constexpr T clog(const T u) {
  return u ? log2p1(u - 1) : static_cast<T>(u);
}
template <typename T> constexpr bool ispow2(const T u) {
  return u and (static_cast<u64>(u) & static_cast<u64>(u - 1)) == 0;
}
template <typename T> constexpr T ceil2(const T u) {
  return static_cast<T>(1) << clog(u);
}
template <typename T> constexpr T floor2(const T u) {
  return u == 0 ? static_cast<T>(0) : static_cast<T>(1) << (log2p1(u) - 1);
}
template <typename T> constexpr bool btest(const T mask, const usize ind) {
  return static_cast<bool>((static_cast<u64>(mask) >> ind) &
                           static_cast<u64>(1));
}
template <typename T> void bset(T &mask, const usize ind) {
  mask |= (static_cast<T>(1) << ind);
}
template <typename T> void breset(T &mask, const usize ind) {
  mask &= ~(static_cast<T>(1) << ind);
}
template <typename T> void bflip(T &mask, const usize ind) {
  mask ^= (static_cast<T>(1) << ind);
}
template <typename T> void bset(T &mask, const usize ind, const bool b) {
  (b ? bset(mask, ind) : breset(mask, ind));
}
template <typename T> constexpr T bcut(const T mask, const usize ind) {
  return ind == 0 ? static_cast<T>(0)
                  : static_cast<T>((static_cast<u64>(mask) << (64 - ind)) >>
                                   (64 - ind));
}
template <typename T> bool chmin(T &a, const T &b) {
  return (a > b ? a = b, true : false);
}
template <typename T> bool chmax(T &a, const T &b) {
  return (a < b ? a = b, true : false);
}
constexpr unsigned int mod = 1000000007;
template <typename T> constexpr T inf_v = std::numeric_limits<T>::max() / 4;
template <typename Real>
constexpr Real pi_v = Real{3.141592653589793238462643383279502884};
auto mfp = [](auto &&f) {
  return [=](auto &&...args) {
    return f(f, std::forward<decltype(args)>(args)...);
  };
};

template <typename T> T in() {
  T v;
  return std::cin >> v, v;
}
template <typename T, typename Uint, usize n, usize i>
T in_v(typename std::enable_if<(i == n), c_arr<Uint, n>>::type) {
  return in<T>();
}
template <typename T, typename Uint, usize n, usize i>
auto in_v(typename std::enable_if<(i < n), c_arr<Uint, n>>::type &szs) {
  const usize s = (usize)szs[i];
  std::vector<decltype(in_v<T, Uint, n, i + 1>(szs))> ans(s);
  for (usize j = 0; j < s; j++) {
    ans[j] = in_v<T, Uint, n, i + 1>(szs);
  }
  return ans;
}
template <typename T, typename Uint, usize n> auto in_v(c_arr<Uint, n> szs) {
  return in_v<T, Uint, n, 0>(szs);
}
template <typename... Types> auto in_t() {
  return std::tuple<std::decay_t<Types>...>{in<Types>()...};
}
struct io_init {
  io_init() {
    std::cin.tie(nullptr), std::ios::sync_with_stdio(false);
    std::cout << std::fixed << std::setprecision(20);
  }
  void clear() { std::cin.tie(), std::ios::sync_with_stdio(true); }
} io_setting;

int out() { return 0; }
template <typename T> int out(const T &v) { return std::cout << v, 0; }
template <typename T> int out(const std::vector<T> &v) {
  for (usize i = 0; i < v.size(); i++) {
    if (i > 0) {
      std::cout << ' ';
    }
    out(v[i]);
  }
  return 0;
}
template <typename T1, typename T2> int out(const std::pair<T1, T2> &v) {
  return out(v.first), std::cout << ' ', out(v.second), 0;
}
template <typename T, typename... Args>
int out(const T &v, const Args... args) {
  return out(v), std::cout << ' ', out(args...), 0;
}
template <typename... Args> int outln(const Args... args) {
  return out(args...), std::cout << '\n', 0;
}
template <typename... Args> int outel(const Args... args) {
  return out(args...), std::cout << std::endl, 0;
}
#define SHOW(...) static_cast<void>(0)
constexpr ull TEN(const usize n) { return n == 0 ? 1ULL : TEN(n - 1) * 10ULL; }

template <typename T, typename Uint, usize n, usize i>
auto make_v(typename std::enable_if<(i == n), c_arr<Uint, n>>::type,
            const T &v = T{}) {
  return v;
}
template <typename T, typename Uint, usize n, usize i>
auto make_v(typename std::enable_if<(i < n), c_arr<Uint, n>>::type szs,
            const T &v = T{}) {
  const usize s = (usize)szs[i];
  return std::vector<decltype(make_v<T, Uint, n, i + 1>(szs, v))>(
      s, make_v<T, Uint, n, i + 1>(szs, v));
}
template <typename T, typename Uint, usize n>
auto make_v(c_arr<Uint, n> szs, const T &t = T{}) {
  return make_v<T, Uint, n, 0>(szs, t);
}
int main() {
  const auto H = in<int>(), W = in<int>();
  auto ass = in_v<int>({H, W});
  using pii = std::pair<int, int>;
  auto next = make_v<pii>({H, W});
  for (int i = 0; i < H; i++) {
    for (int j = 0; j < W; j++) {
      if (i % 2 == 0) {
        next[i][j] = (j == W - 1 ? pii{i + 1, j} : pii{i, j + 1});
      } else {
        next[i][j] = (j == 0 ? pii{i + 1, j} : pii{i, j - 1});
      }
    }
  }
  int y = 0, x = 0;
  std::vector<int> ys, xs, nys, nxs;
  while (y < H) {
    const auto nxt = next[y][x];
    const int ny = nxt.first, nx = nxt.second;

    if (ny < H and ass[y][x] % 2 == 1) {
      ys.push_back(y + 1), xs.push_back(x + 1);
      nys.push_back(ny + 1), nxs.push_back(nx + 1);
      ass[y][x]--, ass[ny][nx]++;
    }
    y = ny, x = nx;
  }
  outln(ys.size());
  for (int i = 0; i < ys.size(); i++) {
    outln(ys[i], xs[i], nys[i], nxs[i]);
  }
  return 0;
}