Problem:
Score : 100 points

Problem Statement

You are given four digits N_1, N_2, N_3 and N_4. Determine if these can be arranged into the sequence of digits "1974".

Constraints

0 \leq N_1, N_2, N_3, N_4 \leq 9

N_1, N_2, N_3 and N_4 are integers.

Input

Input is given from Standard Input in the following format:

N_1 N_2 N_3 N_4

Output

If N_1, N_2, N_3 and N_4 can be arranged into the sequence of digits "1974", print YES; if they cannot, print NO.

Sample Input 1

1 7 9 4

Sample Output 1

YES

We can get 1974 by swapping N_2 and N_3.

Sample Input 2

1 9 7 4

Sample Output 2

YES

We already have 1974 before doing anything.

Sample Input 3

1 2 9 1

Sample Output 3

NO

Sample Input 4

4 9 0 8

Sample Output 4

NO

Solution in C (GCC 5.4.1) (judge verdict: Accepted)

#include <stdio.h>
#include <stdlib.h>
#include <math.h>

int main(){
  int n[4],i,m,k;
  m=0;
  k=0;
  
    for(i=0;i<4;i++){
    scanf("%d",&n[i]);
  }
  
    for(i=0;i<4;i++){
      if(n[i]==1)
        m=m+1;
      else if(n[i]==9)
        m=m+1;
      else if(n[i]==7)
        m=m+1;
      else if(n[i]==4)
        m=m+1;
      else m=0;
      k=k+n[i];

  }
  
  if(k==21 && m==4)
    printf("YES");
  else 
    printf("NO");
  
}