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.*;
  
class Main {
    public static void main(String args[]) {
        Scanner sc =new Scanner(System.in);
        int n= sc.nextInt();
        int i;
        long s=1;
         
        for(i=2;i<=n;i++)
        s*=i;
         
        System.out.println(s);
         
    }
}