[StartCode]
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleApp1
{
    internal class Program
    {
        static void Main(string[] args)
        {
            int[] bag =new int[0];
            bool beOpen = (true);

            while (beOpen == true)
            {
                string command;
                Console.WriteLine("Введите команду :");
                command = Console.ReadLine();

                switch (command)
                {
                    case "exit":
                        beOpen = false;
                        break;

                    case "sum":
                        int sum = 0;

                        for(int i = 0; i < bag.Length; i++)
                        {
                            sum+=bag[i];
                        }

                        Console.WriteLine(sum);
                        break;

                    default:
                        int[] tempBag = new int[bag.Length + 1];

                        for (int i = 0; i < bag.Length; i++)
                        {
                            tempBag[i] = bag[i];
                        }

                        tempBag[tempBag.Length -1] = Convert.ToByte(command);
                        bag = tempBag;
                        continue;
                }
            }
        }
    }
}
[EndCode]