using System;

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            int number;

            unsafe
            {
                int* p = &number;

                *p = 0;

                Console.WriteLine("a: {0}", *p);

                increment((int)p);
                increment((int)p);
                increment((int)p);

                Console.WriteLine("a: {0}", *p);
            }

            Console.ReadKey();
        }

        static void increment(int x)
        {
            unsafe
            {
                int* k = (int*)x;

                *k = *k + 1;
            }
        }
    }
}