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.*;

public class Main {
    public static void main (String[] args) {
        Scanner scanner = new Scanner(System.in);
        
        int n = scanner.nextInt();
        long result = factorial(n);
        System.out.println(result);
    }
    
    public static long factorial(int n) {
        if (n == 0) {
            return 1;
        } 
        return n * factorial(n-1);
    }
}