task17

using System;
using System.Text;

public class Program
{
    public static void Main()
    {
        uint arrayLength = 0;

        int[] numbers = null;
        int[] numbersPrevios = numbers;
        long sumNumbers = 0;
        int parseNumber = 0;
        string input;

        bool isRun = true;
        bool isNumber;

        while (isRun)
        {
            Console.WriteLine("Type number or command : ");
            input = Console.ReadLine();

            isNumber = int.TryParse(input, out parseNumber);

            if (isNumber)
            {
                ++arrayLength;
                numbers = new int[arrayLength];

                for (int i = 0; i < arrayLength - 1; ++i)
                    numbers[i] = numbersPrevios[i];

                numbers[arrayLength - 1] = parseNumber;
                numbersPrevios = numbers;
                sumNumbers += parseNumber;
            }
            else
            {
                switch (input)
                {
                    case "sum":
                        Console.WriteLine("The sum of numbers is : " + sumNumbers);
                        break;
                    case "exit":
                        isRun = false;
                        break;
                    default:
                        Console.WriteLine("You write wrong number or command.");
                        break;
                }
            }
        }
    }
}