func_code_string: #include <bits/stdc++.h>   using namespace std;   string second, pre, suf;   int main() {     ios::sync_with_stdio(false);     cin >> second;     int n = (int)second.size();     int l = 0;     int r = n - 1;     while (l + 1 < r - 1) {       if (second[l] == second[r]) {         pre += second[l];         suf += second[r];       } else {         if (second[l] == second[r - 1])           pre += second[l], suf += second[r - 1];         else if (second[l + 1] == second[r])           pre += second[l + 1], suf += second[r];         else           pre += second[l + 1], suf += second[r - 1];       }       l += 2;       r -= 2;     }     if (n % 4 != 0) {       pre += second[n / 2];     }     reverse(suf.begin(), suf.end());     pre = pre + suf;     cout << pre;     return 0;   }   