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]) = {
    val sc = new java.util.Scanner(System.in)
    val a, b = sc.nextInt
    val x = math.max(a, b)
    val y = math.min(a, b)
    println(gcd(x,y))
  }
  def gcd(x: Int, y: Int) : Int = {
    if (y == 0) x else gcd(y, x%y)
  }
}