import java.math.BigInteger;
import java.util.Scanner;

public class Main {
    static BigInteger fact(int n){
        BigInteger ret = BigInteger.ONE;
        for(int i = 1; i <= n; ++i){
            ret = ret.multiply(BigInteger.valueOf(i));
        }
        return ret;
    }
    public static void main(String[] args){
        Scanner in = new Scanner(System.in);
        int n;
        while(in.hasNext()){
        	n = in.nextInt();
            System.out.println(fact(n));
        }
        in.close();
    }
}