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) {

		//input
		Scanner sc = new Scanner(System.in);
		
		//calculation
		Long ans = 1L;
		for(Long N = sc.nextLong();N>1;N--){
			ans *= N;
		}
		//output
		System.out.println(ans);
	}
}