using System;

public class Program

{

    public static void Main()

    {

        double a=1, b=0;

        while(a > 0)

        {

            Console.WriteLine("enter price of your product");

            a = Double.Parse(Console.ReadLine());

            if (a > 0)

                b = b+a;

        }

        Console.WriteLine("Total:" +b);

    }

}

​