func_code_string: #include <bits/stdc++.h>   using namespace std;   const long double pi = acos(-1);   void boos() {     ios_base ::sync_with_stdio(false);     cin.tie(0);     cout.tie(0);   }   void file() {     freopen( array.in ,  r , stdin);     freopen( array.out ,  w , stdout);   }   const long long INF = 1e9 + 7;   const int INF1 = 998244353;   const long long LLINF = (long long)1e18;   const int INTmx = (int)1e9;   const int N = 2e3 + 1;   int main() {     boos();     string second;     cin >> second;     int kol = 0;     for (int i = 0; i < second.size(); i++) {       if (second[i] ==  a ) kol++;     }     int n = second.size() - kol;     if (n % 2) {       cout <<  :( ;       return 0;     }     int m = n / 2;     int gg = m + kol;     string a, b;     for (int i = 0; i < gg; i++) {       a += second[i];       if (second[i] !=  a ) b += second[i];     }     if (a + b != second) {       cout <<  :( ;       return 0;     }     cout << a;   }   