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;

class Main {

        public static void main(String[] args) {
        
        Scanner scan = new Scanner (System.in);
            
        long n = scan.nextLong();
        long i;
        long d = 1;
        for(i=1;i<=n;i++ ){
        d = d*i;
        }
        System.out.println(d);
       

        }
    }

