import java.util.Scanner;
public class Series
{

    public static void main()
    {
        int n=0,i=0,j=0;
        long sum=0,fact=1;
        Scanner sc=new Scanner(System.in);
        System.out.println("ENTER THE Nth TERM");
        n=sc.nextInt();
        for(i=1;i<=n;i++)
        {
            for(j=1;j<=i;j++)
            {
                fact=fact*j;
            }
            if(i%2==0)
            {
                sum=sum-fact;
            }
            else
            {
                sum=sum+fact;
            }
            fact=1;

        }
        System.out.println("SUM OF SERIES="+sum);
    }
}