func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     ios_base::sync_with_stdio(false), cin.tie(NULL), cout.tie(NULL);     int i, j, k;     int n, m, idx;     string s, s2;     cin >> s;     n = s.length();     int cnt = 0;     for (i = 0; i < n; i++) {       if (s[i] ==  a ) cnt++;     }     k = 0;     idx = 0;     for (i = 0; i < n; i++) {       if (k == cnt) break;       if (s[i] ==  a )         k++, idx = i + 1;       else         s2.push_back(s[i]);     }     k = n - idx;     k -= s2.length();     if (k % 2 == 0) {       k /= 2;       j = idx;       idx += k;       while (k > 0) {         s2.push_back(s[j]);         j++;         k--;       }       k = s.length() - 1;       for (i = s2.length() - 1; i >= 0; i--) {         if (s2[i] != s[k]) {           cout <<  :( ;           return 0;         }         k--;       }       for (i = 0; i < idx; i++) cout << s[i];     } else       cout <<  :( ;     return 0;   }   