func_code_string: #include <bits/stdc++.h>   using namespace std;   const int maxn = 1e5 + 5;   const int mod = 1e9 + 7;   char str[maxn];   long long qp(long long a, long long b) {     long long ret = 1;     while (b) {       if (b & 1) ret = ret * a % mod;       a = a * a % mod;       b >>= 1;     }     return ret;   }   long long inv(long long a) { return qp(a, mod - 2); }   void solve(long long);   int main() {     scanf( %s , str);     long long k;     cin >> k;     solve(k);     return 0;   }   void solve(long long k) {     long long n = (long long)strlen(str);     long long ans = 0;     for (int i = 0; i < n; i++) {       if (str[i] ==  0  || str[i] ==  5 ) {         long long tmp = (qp(2, n * k + i) - qp(2, i) + mod) % mod;         tmp = tmp * inv(qp(2, n) - 1) % mod;         ans = (ans + tmp) % mod;         while (ans < 0) ans += mod;       }     }     cout << ans << endl;     return;   }   