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