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 scanner = new java.util.Scanner(System.in)
    var m, n = scanner.nextInt

    if(m < n) {
      val t = m
      m = n
      n = t
    }

    while(true) {
      if(n == 0) {
        println(m)
        System.exit(0)
      }
      val t = n
      n = m % n
      m = t
    }
  }
}