A. Nearly Lucky Number Solution

#include<bits/stdc++.h>

using namespace std;

int main()

{

     long long int s;

     int l,i;

     cin>>s;

     int flag=0;

     while(s!=0){

        if(s%10==4 || s%10==7 ){

            flag++;

        }

        s/=10;

     }

     if (flag == 4|| flag == 7)

        cout<<"YES"<<endl;

     else

        cout<<"NO"<<endl;

     return 0;

}