static void Main(string[] args)
{
Geek g = new Geek();
g.M1();
g.M2();
g.M3();
g.M4();
g.M5("M5");
Console.ReadLine();
}
public static void M5(this Geek g, string str)
{
Console.WriteLine(str);
}
public static void M4(this Geek g)
{
Console.WriteLine("M4");
}