namespace ConsoleApp1;

using System.Text;

public class Task23
{
    public void Run()
    {
        Console.InputEncoding = Encoding.Unicode;
        Console.OutputEncoding = Encoding.Unicode;

        string sumCommand = "sum";
        string exitCommand = "exit";

        int[] numbers = {};
        int emptyArrayLength = 0;

        bool canExit = false;

        while ( canExit == false )
        {
            Console.WriteLine( "\nEnter commands 'sum' or 'exit' or numbers:" );

            string command = Console.ReadLine().Trim();

            if ( string.Equals( command, exitCommand ) )
            {
                canExit = true;
            }
            else if ( string.Equals( command, sumCommand ) )
            {
                if ( numbers.Length == emptyArrayLength )
                {
                    Console.WriteLine("Array is empty, you can not calculate sum");
                }
                else
                {
                    var arraySum = 0;

                    foreach ( int number in numbers )
                        arraySum += number;

                    Console.WriteLine( $"Sum of array numbers is {arraySum}" );
                }
            }
            else
            {
                int number = int.Parse( command );

                int newNumbersArrayLength = numbers.Length + 1;
                int[] newNumbers = new int[newNumbersArrayLength];

                for ( int i = 0; i < numbers.Length; i++ )
                    newNumbers[i] = numbers[i];

                newNumbers[newNumbers.Length - 1] = number;
                numbers = newNumbers;

                Console.WriteLine( $"Number {number} added" );
            }
        }
    }
}