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 Ans[4]={1,7,9,4};
	int i,f,N;
	
	for(i=0;i<4;i++){
	scanf("%d",&N);
		for(f=0;f<4;f++){
			if(Ans[f]==N){
			Ans[f]=99;
			
			}
		
		}
	}
	
	if(Ans[0]==99&&Ans[1]==99&&Ans[2]==99&&Ans[3]==99){
	printf("YES\n");
	}else{
	printf("NO\n");
	}
	
}