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 d,x,y,z,cc=0,i,max=0;
	scanf("%d%d",&x,&y);
	z=x%y;
	if(x==y)max=x;
	for(d=1;d<=z;d++){
		if(z%d==0 && y%d==0){
			if(cc!=0 && max<d)max=d;
			else if(cc==0){
				max=d;
				cc++;
			}
		}
	}
	printf("%d\n",max);
	return 0;
}