using System;

public class Program

{

    public static void Main()

    {

        int a = 1;

        int b = 0;

            while (a>0)

        {

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

            if (a<0) break;

            else

            {

                b = a + b;

                Console.WriteLine(b); 

            }

            }

        }

    }

​