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 sc = new Scanner(System.in);
long i = sc.nextLong();
long a = 1;
for(;i>0;i--){
a *= i;
}
System.out.println(a);
}
}