func_code_string: #include <bits/stdc++.h>   using namespace std;   int n, k;   string a[2005];   int common[2005][2005];   int main() {     std::ios::sync_with_stdio(false);     cin >> n >> k;     for (int i = 0; i < n; i++) cin >> a[i];     sort(a, a + n);     for (int i = 0; i < n; i++)       for (int j = i + 1; j < n; j++)         for (int k = 0; k < a[i].size() && k < a[j].size(); k++)           if (a[i][k] == a[j][k])             common[i][j] = k + 1;           else             break;     int ans = 0;     for (int i = 0; i < (1 << n); i++)       if (__builtin_popcount(i) == k) {         int cur = 0;         for (int j = 0; j < n; j++)           if (i & (1 << j))             for (int k = j + 1; k < n; k++)               if (i & (1 << k)) cur += common[j][k];         if (cur > ans) ans = cur;       }     cout << ans << endl;     return 0;   }   