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>

main(){

  int a,b,i;

  scanf("%d %d",&a,&b);

  if(b<a){
    i=b;
    b=a;
    a=i;
  }

  for(i=a;i<=b;i--){
    if(a%i==0 && b%i==0)break;
  }
  printf("%d\n",i);

  return 0;
}