func_code_string: #include <bits/stdc++.h>   using namespace std;   void fast() {     ios_base::sync_with_stdio(false);     cin.tie(0);     cout.tie(0);   }   long long cmp(pair<int, int> a, pair<int, int> b) {     return a.second < b.second;   }   int main() {     int n, m;     cin >> n >> m;     char a[n + 1][m + 1];     for (int i = 1; i <= n; i++) {       for (int j = 1; j <= m; j++) {         cin >> a[i][j];       }     }     long long ans = 0;     long long x[n + 1][m + 1];     long long y[n + 1][m + 1];     for (int i = 0; i <= n; i++) {       for (int j = 0; j <= m; j++) {         x[i][j] = 0;         y[i][j] = 0;       }     }     for (int i = 1; i <= n; i++) {       for (int j = 1; j <= m; j++) {         if (a[i][j] ==  0 ) {           x[i][j] = x[i][j - 1] + 1;           y[i][j] = y[i - 1][j] + 1;           long long ymin = y[i][j];           long long xmin = x[i][j];           for (int k = j - x[i][j] + 1; k <= j; k++) {             ymin = min(ymin, y[i][k]);           }           for (int k = i - y[i][j] + 1; k <= i; k++) {             xmin = min(xmin, x[k][j]);           }           long long p1 = ymin + x[i][j];           long long p2 = xmin + y[i][j];           long long p = (max(p1, p2)) * 2;           ans = max(p, ans);         }       }     }     cout << ans << endl;   }   