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