func_code_string: #include <bits/stdc++.h>   using namespace std;   const long double EPS = 1e-3;   const int INF = (long double)(1e9);   const long long mod = (int)(1e+9 + 7);   const int N = (int)(2e3);   int days_month[12] = {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};   long long ekn;   long long inverse;   long long expo(long long b, long long e) {     long long prod = 1;     while (e != 0) {       if (e & 1) prod = (1LL * prod * b) % mod;       b = (1LL * b * b) % mod;       e >>= 1;     }     return prod % mod;   }   int f(int i) {     long long prod = (1LL * expo(2, i) * (ekn - 1)) % mod;     prod = (prod * inverse) % mod;     return prod;   }   int main() {     string s;     cin >> s;     int k;     cin >> k;     int n = int(s.size());     ekn = expo(2, 1LL * k * n);     inverse = expo(expo(2, n) - 1, mod - 2);     int ans = 0;     for (int i = 0; i < n; i++) {       if (s[i] !=  0  && s[i] !=  5 ) continue;       ans += f(i);       if (ans >= mod) ans -= mod;     }     cout << ans;     return 0;   }   