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>

int main(void){

  int n[4];
  for (int i = 0; i < 4; i++) {
    scanf("%d", &n[i]);
  }
  int digit[10];
  for (int i = 0; i < 10; i++) {
    digit[i] = 0;
  }
  for (int i = 0; i < 4; i++) {
    digit[n[i]]++;
  }
  if (digit[1] == 1 && digit[9] == 1 && digit[7] == 1 && digit[4] == 1) {
    printf("YES\n");
  } else {
    printf("NO\n");
  }

  return 0;
}