func_code_string: #include <bits/stdc++.h>   using namespace std;   char a[15];   char rr[15];   char ans[15];   int main() {     int maxx = -99;     cin >> a;     int len = strlen(a);     for (int i = 1; i < 1 << len; i++) {       int cnt = 0;       for (int j = 0; j <= len - 1; j++) {         if (i >> j & 1) rr[++cnt] = a[j];       }       int flag = 0;       for (int l = 1, r = cnt; l <= r; l++, r--) {         if (rr[l] != rr[r]) {           flag = 1;           break;         }       }       if (flag == 0) {         if (strcmp(ans + 1, rr + 1) < 0) {           for (int i = 1; i <= 14; i++) {             if (i <= cnt)               ans[i] = rr[i];             else               ans[i] =   0 ;           }         }       }     }     cout << ans + 1 << endl;   }   