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(void)
{
  int x,y;
  int i;
  int j;
  int ans;
  
  scanf("%d",&x);
  scanf("%d",&y);

  if (x>y) j=x;
  else j=y;

  if (x==y) ans=x;
  else {
    for (i=1; i<j/2+1; i++) {
      if (x%i==0 && y%i==0) ans=i;
    }
  }
  printf("%d\n",ans);
  return 0;
}