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: Accepted)

#include <stdio.h>

int main()
{
  int x,y,i,j=0;
  int xy,yaku[100];
    
    scanf("%d%d",&x,&y);
    
    if(x>=y) xy=x%y;
    else xy=y%x;
    
    for(i=1; i<=xy; i++)
    {
      
      if(y%i==0 && xy%i==0)
	{
	  yaku[j]=i;
	  j++;
	}
        
    }
    printf("%d\n",yaku[j-1]);
    return 0;
}