Factorial

import java.util.Scanner;
public class Main{
    long a[] = new long[100];
    void fac(){
        a[0]=1;
        a[1]=1;
        for(int i=2;i<=40;i++){
            a[i]=a[i-1]*i;
        }
    }
    public static void main(String args[]){
        Main mn = new Main();
        mn.fac();
        Scanner cin = new Scanner(System.in);
        while(cin.hasNext()){
            int n = cin.nextInt();
            System.out.println(mn.a[n]);
        }
    }
}