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>

void Swap(int *,int *);

int main(){

  int x,y;
  int result;
  int i;

  scanf("%d %d",&x,&y);

  if(x>y){
    Swap(&x,&y);
  }

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

  return 0;
}

void Swap(int *x, int *y){
  int keep;

  keep=*x;
  *x=*y;
  *y=keep;

}