func_code_string: #include <bits/stdc++.h>   using namespace std;   signed main() {     ios_base::sync_with_stdio(false);     cin.tie(NULL);     string s;     cin >> s;     long long l = s.length();     vector<char> s1;     long long pos = -1;     for (long long i = 0; i < l; i++) {       if (s[i] ==  a )         pos = i;       else         s1.push_back(s[i]);     }     long long l2 = s1.size();     long long ri = l - 1 - pos;     long long le = l2 - ri;     if (l2 % 2 != 0 || le > ri)       cout <<  :( ;     else {       long long j = l2 / 2;       bool flag = true;       for (long long i = 0; i < j; i++) {         if (s1[i] != s1[i + j]) {           flag = false;           break;         }       }       if (!flag)         cout <<  :( ;       else {         for (long long i = 0; i < l - j; i++) cout << s[i];       }     }   }   