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.

Example

Input

5


Output

120
import java.util.Scanner;

public class Main{
  public static void main(String args[]){
    Scanner s=new Scanner(System.in);
    long n=s.nextInt(),a=1;
  	for(int i=1;i<=n;++i)a*=i;
    System.out.println(a);
  }
}