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: Wrong Answer)

object Main extends App {
  val n = scala.io.StdIn.readLine.toInt
  println(func(n))
  def func(n: Int): Int = {
    if(n == 0) 1 else n * func(n - 1)
  }
}