الخوارزمياتحساب قيمة الـ Factorial للعدد - التمرين التاسع

import java.util.Scanner;
 
public class Factorial {
 
    public static void main (String[] args) {
 
        Scanner input = new Scanner(System.in);
 
        int N;
        int F = 1;
        double S = 0;
 
        System.out.print("Enter a number For N: ");
        N = input.nextInt();
 
        for (int i=1; i<=N; i++)
        {
            F = F * (i+1);
 
            if (i%2 == 1)
            {
                S = S - (i+F);
            }
            else
            {
                S = S + (i+F);
            }
        }
 
        System.out.print("S = " +S+ "\n");
 
    }
 
}