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;

public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		long a, b;
		a = sc.nextLong();
		b = sc.nextLong();
		long tmp = 0;
		if (a < b) {
			tmp = a;
			a = b;
			b = tmp;
		}
		while (a % b != 0) {
			tmp = a;
			a = b;
			b = tmp % b;
		}
		System.out.println(b);
	}
}