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,c,ans;

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

  for(i = 1;i <= a;i++){
    if(i > b) break;
    if(a % i == 0 && b % i == 0){
      ans = i;
    }
  }
  printf("%d\n",ans);

  return 0;
}