func_code_string: #include <bits/stdc++.h>   using namespace std;   int main(void) {     int n, m;     cin >> n >> m;     vector<string> xs(n);     for (int i = 0; i < n; i++) cin >> xs[i];     int cur = 0;     int curB = 0;     set<int> ans;     for (int i = 0; i < xs.size() - 1; i++) {       int j = 0;       while (j < xs[i].size()) {         if (xs[i][j] != xs[i + 1][j] && !ans.count(j)) {           break;         }         j++;       }       if (j < m && xs[i][j] > xs[i + 1][j]) {         ans.insert(j);         i = -1;       }     }     cout << ans.size();     return 0;   }   