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 sc = new Scanner(System.in);
		int num1 = sc.nextInt();
		int num2 = sc.nextInt();
		int amari;
		while(0 < 1) {
			amari = num1 % num2;
			if(amari == 0) break;
			num1 = num2;
			num2 = amari;
		}
		System.out.println(num2);
		sc.close();
	}	
}