хэши пацанские

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>

using namespace std;
using namespace __gnu_pbds;

using ll = long long;
using ld = long double;
using ull = unsigned long long;
using pii = pair<int, int>;

const int base1 = 30;
const int base2 = 31;

ull ubinpow(ull x, int p) {
    ull ans = 1;
    while (p) {
        if (p & 1)
            ans *= x;
        x *= x;
        p >>= 1;
    }
    return ans;
}

struct Coord {
    int x, y;
};

void solve() {
    int n, m;
    cin >> n >> m;
    vector<vector<char>> a(n, vector<char>(m));
    vector<vector<ull>> h(n + 1, vector<ull>(m + 1));

    for (int i = 0; i < n; ++i) {
        for (int j = 0; j < m; ++j) {
            cin >> a[i][j];
        }
    }

    for (int i = 1; i <= n; ++i) {
        for (int j = 1; j <= m; ++j) {
            int v = a[i - 1][j - 1] - 'a';
            h[i][j] = h[i - 1][j] * base1 + h[i][j - 1] * base2 - h[i - 1][j - 1] * base1 * base2 + v;
        }
    }

    gp_hash_table<ull, Coord> found;

    for (int k = min(n, m); k >= 1; --k) {
        for (int i = k; i <= n; ++i) {
            for (int j = k; j <= m; ++j) {
                ull cur_hash = h[i][j] - h[i - k][j] * ubinpow(base1, k) - h[i][j - k] * ubinpow(base2, k);
                cur_hash += h[i - k][j - k] * ubinpow(base1 * base2, k);

                if (found.find(cur_hash) != found.end()) {
                    Coord crd = found[cur_hash];
                    int x = crd.x;
                    int y = crd.y;

                    cout << k << '\n';
                    cout << x - k + 1 << ' ' << y - k + 1 << '\n';
                    cout << i - k + 1 << ' ' << j - k + 1 << '\n';
                    return;
                }
                found[cur_hash] = {i, j};
            }
        }
    }

    cout << 0 << '\n';
}

signed main() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    int t = 1;
    //cin >> t;
    while (t--) {
        solve();
    }
}