Problem:
Factorial

Write a program which reads an integer n and prints the factorial of n. You can assume that n ≤ 20.

Input

An integer n (1 ≤ n ≤ 20) in a line.

Output

Print the factorial of n in a line.

Sample Input

5

Output for the Sample Input

120

Solution in Scala (judge verdict: Accepted)

object Main {
	def fact(n: Int) : BigInt = n match{
	  case 0 => 1
	  case _ => n * fact(n-1)
	}
	
    def main(args:Array[String]) = {
        val sc = new java.util.Scanner(System.in)
        while(sc.hasNext){
            println(fact(sc.nextInt))
        }
    }
}