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 i,j,a,b;
  int a1,b1,c;
  scanf("%d %d",&a,&b);

  for(i=1;i<=a;i++){
    a1=a%i;
    if(a1==0){
      for(j=1;j<=b;j++){
	b1=b%j;
	if(b1==0){
	  if(i==j){
	    c=i;
	  }
	}
      }
    }
  }
  printf("%d\n",c);
  return 0;
}