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(){

	int x, y, a, b, d, i;

	scanf("%d %d", &x, &y);

	if(x<=y){
		a = x;
		b = y%x;
	}else{
		a = y;
		b = x%y;
	}

	for(i=1; i<=a; i++){
		if(a%i==0 && b%i==0){
			d = i;
		}
	}

	printf("%d\n", d);

	return 0;
}