Algorithm
Petya loves lucky numbers. We all know that lucky numbers are the positive integers whose decimal representations contain only the lucky digits 4 and 7. For example, numbers 47, 744, 4 are lucky and 5, 17, 467 are not.
Unfortunately, not all numbers are lucky. Petya calls a number nearly lucky if the number of lucky digits in it is a lucky number. He wonders whether number n is a nearly lucky number.
The only line contains an integer n (1 ≤ n ≤ 1018).
Please do not use the %lld specificator to read or write 64-bit numbers in ะก++. It is preferred to use the cin, cout streams or the %I64d specificator.
Print on the single line "YES" if n is a nearly lucky number. Otherwise, print "NO" (without the quotes).
40047
NO
7747774
YES
1000000000000000000
NO
In the first sample there are 3 lucky digits (first one and last two), so the answer is "NO".
In the second sample there are 7 lucky digits, 7 is lucky number, so the answer is "YES".
In the third sample there are no lucky digits, so the answer is "NO".
Code Examples
#1 Code Example with C++ Programming
Code -
C++ Programming
#include<iostream>
using namespace std;
int main(){
long long n;
cin>>n;
int check = 0;
int rem;
while(n != 0){
rem = n%10;
n /= 10;
if(rem == 7 || rem == 4){
check++;
}
}
if(check != 4 && check != 7){
cout<<"NO";
}
else{
cout<<"YES";
}
return 0;
}Input
Output
Demonstration
Codeforces solution 110-A A. Nearly Lucky Number 110-A Nearly Lucky Codeforces solution