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,min,gcd=1;
  scanf("%d%d",&x,&y);
  if(x>y)
    min = y;
  else min =x;

  i =2;
  while(min >= i){
    if(x%i == 0 && y%i ==0){
      x /= i;
      y /= i;
      min /= i;
      gcd *= i;
      continue;
    }
    i++;
  }
  printf("%d\n",gcd);
  return 0;
}