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 PHP (5.6.30) (judge verdict: Accepted)

<?php
$a = explode(" ",trim(fgets(STDIN)));
$w = 0;
$x = 0;
$y = 0;
$z = 0;
foreach($a as $value){
if($value == 1){
$w = 1;
}
elseif($value == 4){
$x = 1;
}
elseif($value == 7){
$y = 1;
}
elseif($value == 9){
$z = 1;
}
}
if($w+$x+$y+$z==4){
echo 'YES';
}else{
echo 'NO';
}