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 JAVA (judge verdict: Accepted)

import java.util.Scanner;

class Main{
	public static void main(String[] args){
		Scanner stdIn=new Scanner(System.in);
		int x=stdIn.nextInt(),y=stdIn.nextInt(),d;
		if(y>x){
			d=x;
			x=y;
			y=d;
		}
		while(y>0){
			d=x%y;
			x=y;
			y=d;
		}
		System.out.println(x);
	}
}