Problem:
Greatest Common Divisor

Write a program which finds the greatest common divisor of two natural numbers a and b

Input

a and b are given in a line sparated by a single space.

Output

Output the greatest common divisor of a and b.

Constrants

1 ≤ a, b ≤ 109

Hint

You can use the following observation:

For integers x and y, if x ≥ y, then gcd(x, y) = gcd(y, x%y)

Sample Input 1

54 20

Sample Output 1

2

Sample Input 2

147 105

Sample Output 2

21

Solution in PHP (judge verdict: Time Limit Exceeded)

<?php
fscanf(STDIN, "%d %d", $x, $y);

$array = array($x,$y);
$n = min($array);
$yakusu = array();

for($i = 1; $i <= $n; $i++){
    if($x % $i == 0 && $y % $i == 0){
        $yakusu[] = $i;
    }
}

$max_yakusu = max($yakusu);
echo $max_yakusu.PHP_EOL;