import java.util.Scanner;


public class SumSeries
{
    public static int sum(int no)
    {
        if (no == 1)
            return(1);
        else 
            return(no + sum(no-1));
     }

     public static void main(String [] args)
     {
         int last;
         int total;
         Scanner in = new Scanner(System.in);

         System.out.print("Enter the last number: ");
         last = in.nextInt();
         total = sum(last);
         System.out.println("The sum of the series from " +
           "1 to " + last + " is " + total);

    }
}