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<iostream>
int gcd(int x,int y)
{
  int i;
  int gcd,min;
  if(x<y){
    min=x;
  }else{
    min=y;
  }
    for(i=min;i>=1;--i){
      if(x%i==0&&y%i==0){
	gcd=i;
	break;
      }
    }
    return gcd;
}

int main()
{
	int i;
	int x,y;
	int gcdd;
	std::cin>>x>>y;
  gcdd=gcd(x,y);
  std::cout<<gcdd<<"\n";
}