Update 110A - Nearly Lucky Number.cpp

[har3927]

#include <bits/stdc++.h>

using namespace std;

int main()
{
string s;
cin>>s;
int n=s.length();
int count=0;
for(int i=0;i<n;i++){
if(s[i]=='4'||s[i]=='7'){
count++;
}
}
if(count==4||count==7){
cout<<"YES";
}
else{
cout<<"NO";
}

return 0;

}