using System;

public class Program

{

    public static void Main()

    {

        Console.WriteLine("lets use the computer to add conscutive numbers");

        int firstNum;

        int lastNum;

        int sumNum = 0;

        Console.WriteLine("please enter your starting number");

        firstNum = Convert.ToInt32(Console.ReadLine());

        Console.WriteLine("please enter your final number of the series");

        lastNum = Convert.ToInt32(Console.ReadLine());

        while(firstNum <= lastNum)

        {

        sumNum = sumNum + firstNum;

        firstNum ++;

        }

        Console.WriteLine("the sum of the consecutive numbers is: {0}", sumNum);

    }

}