func_code_string: #include <bits/stdc++.h>   using namespace std;   template <class c>   struct rge {     c b, e;   };   template <class c>   rge<c> range(c i, c j) {     return rge<c>{i, j};   }   template <class c>   auto dud(c* x) -> decltype(cerr << *x, 0);   template <class c>   char dud(...);   struct debug {     template <class c>     debug& operator<<(const c&) {       return *this;     }   };   void solve() {     int n, m;     cin >> n >> m;     vector<vector<char> > v(n + 1, vector<char>(m + 1));     for (int i = 1; i <= n; ++i) {       for (int j = 1; j <= m; ++j) {         cin >> v[i][j];       }     }     vector<vector<int> > pf(n + 1, vector<int>(m + 1));     for (int i = 1; i <= n; ++i) {       for (int j = 1; j <= m; ++j) {         pf[i][j] = pf[i - 1][j] + pf[i][j - 1] - pf[i - 1][j - 1];         pf[i][j] += ((v[i][j] ==  X ) ? 1 : 0);       }     }     auto get = [&](int x, int y, int x1, int y1) {       return (pf[x1][y1] - pf[x1][y - 1] - pf[x - 1][y1] + pf[x - 1][y - 1]);     };     auto check = [&](int side) {       vector<vector<int> > add(n + 1, vector<int>(m + 1));       for (int i = 1; i + 2 * side <= n; ++i) {         for (int j = 1; j + 2 * side <= m; ++j) {           long long area = (2 * side + 1) * (2 * side + 1);           if (get(i, j, i + 2 * side, j + 2 * side) == area) {             ++add[i][j];             if (i + 2 * side < n) --add[i + 2 * side + 1][j];             if (j + 2 * side < m) --add[i][j + 2 * side + 1];             if (i + 2 * side < n && j + 2 * side < m)               ++add[i + 2 * side + 1][j + 2 * side + 1];           }         }       }       vector<vector<int> > pf1(n + 1, vector<int>(m + 1));       for (int i = 1; i <= n; ++i) {         for (int j = 1; j <= m; ++j) {           pf1[i][j] =               pf1[i - 1][j] + pf1[i][j - 1] - pf1[i - 1][j - 1] + add[i][j];           int a = !!pf1[i][j], b = ((v[i][j] ==  X ) ? 1 : 0);           if (a ^ b) return 0;         }       }       return 1;     };     int l = 0, r = min(n, m), mid, ans = 1;     while (l <= r) {       mid = l + r >> 1;       if (check(mid))         ans = mid, l = mid + 1;       else         r = mid - 1;     }     cout << ans <<   n ;     int side = ans;     vector<vector<char> > res(n + 1, vector<char>(m + 1,  . ));     for (int i = 1; i <= n; ++i) {       for (int j = 1; j <= m; ++j) {         if (i + 2 * side <= n && j + 2 * side <= m) {           long long area = (2 * side + 1) * (2 * side + 1);           if (get(i, j, i + 2 * side, j + 2 * side) == area)             res[i + side][j + side] =  X ;         }       }     }     for (int i = 1; i <= n; ++i) {       for (int j = 1; j <= m; ++j) cout << res[i][j];       cout <<   n ;     }   }   int main() {     ios_base::sync_with_stdio(false);     cin.tie(0);     cout.tie(0);     int q = 1;     while (q--) solve();   }   