GCD scala

object GCD extends App {

  println(gcd(3, 0))
  println(gcd(2, 1))
  println(gcd(1, 2))
  println(gcd(2, 4))
  println(gcd(4, 2))
  println(gcd(2, 3))
  println(gcd(3, 2))
  println(gcd(10, 100))
  println(gcd(100, 10))
  println(gcd(634, 28))
  println(gcd(7*13, 7*16))
  //println(gcd(-7*13, 7*16))

  def gcd(a: Int, b: Int): Int = b match {
    case 0 => a
    case _ => gcd(b, a % b)
  }

}