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# (Mono 4.6.2.0) (judge verdict: Accepted)

using System;
using System.Collections.Generic;
using System.Linq;

class Program
{
    static void Main()
    {
        Console.WriteLine(Solve());
        return;

    }

    public static string Solve()
    {
        string[] str = Console.ReadLine().Split(' ');
        int[] numbers = new int[4];
        for(int i = 0;i<4;i++)
        {
            numbers[i] = int.Parse(str[i]);
        }
        Array.Sort(numbers);
        //Console.WriteLine("[{0}]", string.Join(", ", numbers));
        if (numbers[0] == 1 && numbers[1] == 4 && numbers[2] == 7 && numbers[3] == 9)
        {
            return "YES";
        }

        return "NO";
    }
}