func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     string a, b, s;     cin >> s;     vector<string> g;     for (long long i = 0; i < s.length(); i++) {       a += s[i];       if (s[i] !=  a ) {         b += s[i];       }       if (a.length() + b.length() == s.length()) {         break;       }     }     if (s == a + b) {       cout << a;     } else {       cout <<  :(  << endl;     }     return 0;   }   