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();

        long res = 1;
        for (int i = 1; i <= n; i++) {
            res *= i;
        }

        System.out.println(res);
    }
}