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 <stdlib.h>

int main (){
  int x,y,i,v;
  
  scanf("%d%d",&x,&y);

  if(x < 1 || y < 1 || x > 1000000000 || y > 1000000000){
    printf("Please type 1 to 1000000000.");
    exit(1);
  }


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