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>

/*x,y?????§?°?????????\???????????\??????????????????????????????????????????????????¨???????????§??¬?´???°???????????¢??°*/
int gcd(int x, int y) {
	int temp;
	while (x) {
		if (y > x) {
			temp = x;
			x = y;
			y = temp;
		}
		else if (x > y) {
			x = x%y;
		}
		
	}
		return y;
	
}

int main(void) {
	int x, y;
	scanf("%d %d", &x, &y);
	printf("%d\n", gcd(x,y));
	return 0;
}