#include <bits/stdc++.h>   using namespace std;   int main() {     long long s;     scanf( %I64d , &s);     long long d = s;     int n = 0;     while (s > 0) {       d /= 10;       d *= 10;       int a = s - d;       if (a == 4 || a == 7) {         n++;       }       s /= 10;       d = s;     }     if (n == 0) {       printf( NO );       return 0;     }     d = n;     while (n > 0) {       d /= 10;       d *= 10;       int a = n - d;       if (a != 4 && a != 7) {         printf( NO );         return 0;       }       n /= 10;       d = n;     }     printf( YES );   }   