public class mysingleton
{
　private static readonly mysingleton _theoneandonly;
　static mysingleton()
　{
　　_theoneandonly = new mysingleton();
　}
　public static mysingleton theonly
　{
　　get{ return _theoneandonly; }
　}

　/// <summary>
　/// private constructor to avoid object created from outside
　/// </summary>

　private mysingleton()
　{}
}

class a
{
　public static int x = b.y;
　static a()
　{
　　++x;
　}
}

class b
{
　public static int y = a.x;
　static b()
　{
　　++y;
　}
}

debug.writeline( a.x.tostring() );
debug.writeline( b.y.tostring() );

debug.writeline( a.x.tostring() );