running-total.cs

void Main() {
  string line;
  int runningTotal = 0, input = 0;
  do {

    line = Console.ReadLine();
    if (Int32.TryParse(line, out input)) {
      runningTotal += input;
      Console.WriteLine(runningTotal);
    } else if (line == "quit" || line == null) {
      return;
    }
  } while (line != null);
}