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)

object Main {
  def main(args: Array[String]): Unit = {
    val Array(x, y, _*) = io.StdIn.readLine().split(" ").map(_.toInt)
    println(gcd(x, y))
  }

  @annotation.tailrec
  def gcd(x: Int, y: Int): Int = {
    if (y == 0)
      x
    else if (x > y)
      gcd(y, x % y)
    else
      gcd(x, y % x)
  }
}