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>

#define NUMBER 4

void bsort(int a[],int n)
{
  int i,j;

  for(i = 0; i < n -1;i++){
    for (j = n-1; j>i-1; j--){
      if(a[j-1]>a[j]){
        int temp = a[j];
        a[j] = a[j-1];
        a[j-1] = temp;
      }
    }
  }
}

int main(void)
{
  int i;
  int a[NUMBER];

  for(i =0; i<NUMBER; i++)
    scanf("%d",&a[i]);

  bsort(a,NUMBER);

  if(a[0]==1&&a[1]==4&&a[2]==7&&a[3]==9)
   printf("YES");
  else
   printf("NO");

  return 0;
}