func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     {       long long int i, j, k, y, n, x, m, a, b, ans = 0, sum = 0, cnt = 0;       long long int c, mx = 0;       string s, z, taj =  YES ;       cin >> s;       map<char, long long int> mp;       n = s.size();       for (i = 0; i < n; i++) mp[s[i]]++;       if (!mp[ 4 ] and !mp[ 7 ])         cout << -1;       else if (mp[ 4 ] >= mp[ 7 ])         cout << 4;       else         cout << 7;       printf(  n );     }     return 0;   }   