//JAVA 大數階乘 
import java.math.*;
import java.util.Scanner;
 
public class LargeNumber{
    public static void main(String[] args){
        BigInteger ans = BigInteger.ONE;
        Scanner cin = new Scanner(System.in);
        int n = cin.nextInt();
        for(int i = 1; i <= n; i++){
            ans = ans.multiply(new BigInteger(i+""));
        }
        System.out.println(ans);
    }
 
}