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

public class Solution {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);

        int n = scanner.nextInt();

        BigInteger fact = BigInteger.ONE;

        for (int i = 2; i <= n; i++) {
            fact = fact.multiply(BigInteger.valueOf(i));
        }

        System.out.println(fact);
    }
}