private static bool valueWritten = false;
private static int sharedValue = 0;

private static void ThreadOneStart() {
	sharedValue = 1000;
	valueWritten = true;
}

private static void ThreadTwoStart() {
	if (valueWritten) Console.Write(sharedValue == 1000 ? String.Empty : "!!!");
}

static unsafe void Main(string[] args) {
	Thread threadOne = new Thread(ThreadOneStart);
	Thread threadTwo = new Thread(ThreadTwoStart);

	threadOne.Start();
	threadTwo.Start();

	threadOne.Join();
	threadTwo.Join();

	Console.ReadKey();
}