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 C (judge verdict: Time Limit Exceeded)

#include <stdio.h>

int main(void)
{
	int x,y,d;
	scanf("%d%d",&x,&y);
	if(x>y){
		d=x;
		x=y;
		y=d;
	}
	for(d=x;d>0;d--){
		if(x%d==0&&y%x%d==0){
			printf("%d\n",d);
			break;
		}
	}
	return 0;
}