class Program1
    {
        [ThreadStatic]
        static int x;

        static void Main(string[] args)
        {
            Program1 p1 = new Program1();
            x = 10;  // initial value
            new Thread(delegate() { p1.GetValue(); }).Start();
            new Thread(delegate() { p1.SetValue(); }).Start();
            new Thread(delegate() { p1.GetValue(); }).Start();
            Console.WriteLine(Program1.x);
        }

        void SetValue()
        {
            x = 100;
            Program1 p2 = new Program1();
            x = 50;
            p2.GetValue();
        }

        void GetValue()
        {
            Console.WriteLine(x);
        }
    }