using System;

public class Program

{

    public static void Main()

    {

        var sum = 0;

​

        while (true)

        {

            Console.WriteLine("Enter a number or ok to exit:");

            if (Console.ReadLine() == "ok") break;

            sum += Convert.ToInt32(Console.ReadLine());

            Console.WriteLine(sum);

        }

        /*

        while (true)

        {

            Console.Write("Enter a number (or 'ok' to exit): ");

            var input = Console.ReadLine();

            if (input.ToLower() == "ok")

                break;

            sum += Convert.ToInt32(input);

        }

        Console.WriteLine("Sum of all numbers is: " + sum);

        */

    }

}