func_code_string: #include <bits/stdc++.h>   using namespace std;   using ll = long long;   int main() {     ios::sync_with_stdio(false);     cin.tie(0);     int n, m;     cin >> n >> m;     vector<string> s(n + 2);     for (int i = 1; i <= n; i++) {       cin >> s[i];       s[i] =  .  + s[i] +  . ;     }     s[0] = s[n + 1] = string(m + 2,  . );     vector<vector<int>> d(n + 2, vector<int>(m + 2, 1e9));     priority_queue<pair<int, pair<int, int>>, vector<pair<int, pair<int, int>>>,                    greater<pair<int, pair<int, int>>>>         pq;     for (int i = 0; i < n + 2; i++) {       for (int j = 0; j < m + 2; j++) {         if (s[i][j] ==  . ) {           d[i][j] = 0;           pq.push({0, {i, j}});         }       }     }     while (!pq.empty()) {       int dis = pq.top().first;       int i, j;       tie(i, j) = pq.top().second;       pq.pop();       if (dis > d[i][j]) continue;       for (int di = -1; di <= 1; di++) {         if (i == 0 && di == -1) continue;         if (i == n + 1 && di == 1) continue;         for (int dj = -1; dj <= 1; dj++) {           if (j == 0 && dj == -1) continue;           if (j == m + 1 && dj == 1) continue;           if (d[i + di][j + dj] > d[i][j] + 1) {             d[i + di][j + dj] = d[i][j] + 1;             pq.push({d[i + di][j + dj], {i + di, j + dj}});           }         }       }     }     int mx = 0;     vector<vector<pair<int, int>>> x(2000);     for (int i = 0; i < n + 2; i++) {       for (int j = 0; j < m + 2; j++) {         mx = max(mx, d[i][j]);         if (d[i][j] > 0) {           x[d[i][j]].emplace_back(i, j);         }       }     }     vector<vector<int>> e;     int ans = mx;     int lo = 1, hi = mx + 1;     while (lo + 1 < hi) {       e = vector<vector<int>>(n + 2, vector<int>(m + 2));       for (int i = 0; i < n + 2; i++) e[i][0] = e[i][m + 1] = 1e9;       for (int i = 0; i < m + 2; i++) e[0][i] = e[n + 1][i] = 1e9;       int mid = (lo + hi) / 2;       queue<pair<int, int>> que;       for (auto p : x[mid]) {         if (d[p.first][p.second] == mid) {           que.push({p.first, p.second});           e[p.first][p.second] = mid;           ans = mid;         }       }       int tmp = mid - 1;       while (que.size() && tmp) {         for (int jj = que.size(); jj > 0; jj--) {           int i, j;           tie(i, j) = que.front();           que.pop();           for (int di = -1; di <= 1; di++) {             for (int dj = -1; dj <= 1; dj++) {               if (e[i + di][j + dj] != mid) {                 e[i + di][j + dj] = mid;                 que.push({i + di, j + dj});               }             }           }         }         tmp--;       }       bool ok = true;       for (int i = 1; i < n + 1; i++) {         for (int j = 1; j < m + 1; j++) {           if (d[i][j] != 0 && d[i][j] < mid && e[i][j] == 0) {             ok = false;             break;           }         }         if (!ok) break;       }       if (ok) {         lo = mid;       } else {         hi = mid;       }     }     ans = lo - 1;     vector<string> res(n, string(m,  . ));     for (int i = 1; i <= n; i++) {       for (int j = 1; j <= m; j++) {         if (s[i][j] ==  X ) {           if (d[i][j] > ans) {             res[i - 1][j - 1] =  X ;           }         }       }     }     cout << ans <<   n ;     for (int i = 0; i < n; i++) {       cout << res[i] <<   n ;     }     return 0;   }   