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 Java8 (OpenJDK 1.8.0) (judge verdict: Wrong Answer)

import java.util.Scanner;
import java.lang.Math;
import java.util.ArrayList;
import java.util.List;
//List<String> color = new ArrayList<>();
//int[] n = new int[k];

class Main {
	public static void main(String[] args) {
		Scanner stdIn = new Scanner(System.in);
		List<Integer> n = new ArrayList<>();
		int[] n1 = new int[4];
		for (int i = 0; i < 4; i++)
			n1[i] = stdIn.nextInt();
			
		for (int i = 0; i < 4; i++)
			n.add(n1[i]);

		if (n.contains(1)) {
			int b = n.indexOf(1);
			n.remove(b); 
		}
		if (n.contains(9)) {
			int c = n.indexOf(9);
			n.remove(c); 
		}
		if (n.contains(7)) {
			int d = n.indexOf(7);
			n.remove(d); 
		}
		if (n.contains(4)) {
			int e = n.indexOf(4);
			n.remove(e); 
		}

		if (n.isEmpty() == true) 
			System.out.println("Yes");
		else
			System.out.println("No");
	}
}