func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     int a, b;     cin >> a >> b;     int p;     string s[100];     string s1, s2, s3 =   , s4 =   , s5 =   , s6, s7, s8, s9;     for (int i = 0; i < a; i++) {       int p = 0;       cin >> s[i];       s6 = s[i];       reverse(s6.begin(), s6.end());       if (s[i] == s6) {         s7 = s[i];       }     }     for (int i = 0; i < a - 1; i++) {       s2 = s[i];       reverse(s[i].begin(), s[i].end());       for (int j = i + 1; j < a; j++) {         if (s[i] == s[j]) {           s3 = s3 + s2;           s8 = s[j];           s4 = s8 + s4;         }       }     }     s9 = s3 + s7 + s4;     cout << s9.size() << endl;     int l = s9.size();     if (l != 0) {       cout << s3 + s7 + s4 << endl;     }   }   