internal class Program
{
static void Main(string[] args)
{
string stopWord = "exit";
bool isWork = true;

while (isWork)
{
Console.Write("еще не вышел? ");
string userInput = Console.ReadLine();

if (userInput == stopWord)
{
isWork = false;
}
}

Console.WriteLine("Ура!");
Console.ReadKey();
}
}