LP10475.cpp

#include <bits/stdc++.h>
using namespace std;

vector<int> buildnxt(string& s, int n) {
    vector<int> nxt(n+1);
    nxt[1] = 0;
    for (int i = 2; i <= n; i++) {
        nxt[i] = nxt[i-1];
        while (nxt[i] && s[nxt[i] + 1] != s[i]) nxt[i] = nxt[nxt[i]];
        nxt[i] += s[nxt[i] + 1] == s[i];
    }
    return nxt;
}

int solve(vector<string>& A, int n, int m) {
    vector<int> nxt, cnt(m+1);
    for (int i = 1; i <= n; i++) {
        string& s = A[i];
        nxt = buildnxt(s, m);
        for (int j = nxt[m]; ; j = nxt[j]) {
            cnt[m - j]++;
            if (!j) break;
        }
    }
    for (int i = 1; i <= m; i++) if (cnt[i] == n) return i;
    assert(false);
}

signed main() {
    ios::sync_with_stdio(false); cin.tie(0); cout.tie(0);
    int R, C;
    cin >> R >> C;
    vector<string> A(R+1), AT(C+1);
    for (int i = 1; i <= R; i++) {
        cin >> A[i];
        A[i] = ' ' + A[i];
    }
    for (int i = 1; i <= C; i++) {
        AT[i] = " ";
        for (int j = 1; j <= R; j++) {
            AT[i] += A[j][i];
        }
    }
    cout << solve(A, R, C) * solve(AT, C, R) << '\n';
    return 0;
}