import java.util.Scanner;
 
public class Main {
    public static long factorial(int n) {
        if (n < 0) {
            return 0; // Factorial is not defined for negative numbers
        }
 
        long result = 1;
        for (int i = 2; i <= n; i++) {
            result = result * i;
        }
        return result;
    }
 
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
 
        int n = scanner.nextInt();
 
        System.out.println(factorial(n));
 
        scanner.close();
    }
}

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MTU=

15