func_code_string: #include <bits/stdc++.h>   using namespace std;   string mask(int a) {     string ans;     int x = a;     while (x) {       if (x % 10 == 4 || x % 10 == 7) ans.insert(ans.begin(), x % 10 +  0 );       x /= 10;     }     return ans;   }   int main() {     string b;     int a;     cin >> a >> b;     a++;     while (mask(a) != b) a++;     cout << a;   }   