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 Scala (judge verdict: Accepted)

import scala.io.StdIn.readLine;
object Main {
    def main(args: Array[String]): Unit = {
        val Array(x, y) = readLine.split(" ").map(_.toInt);
        println(gcd(x, y));
    }
    def gcd(x: Int, y: Int): Int = {
        if (x < y) {
            gcd(y, x);
        } else if (x % y == 0) {
            y;
        } else {
            gcd(y, x % y);
        }
    }
}