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>
#include <math.h>
int main()
{
  int x, y, n, d;
  
  scanf("%d%d", &x, &y);
  
  n = fmin(x,y);

  for(d=n; d>=1; d--){
    if(x%d==0 && y%d==0){
      printf("%d\n", d);
      break;
    }
  }
  
  return 0;
}