program(vartual and override)

{
 C c1=new C();
B b1=c1;
A aa=b1;  // or c1;
int r1=c1.m(10,20);
int r2=b1.m(10,5);
int r3=a1.m(10,5);
Response.Write(r1+"<br/>"+r2+"<br/>"+r3+"<br/>");
Public class A
{
   public vartual int m(int x,int y)
      {
         return x+y;
       }
 }
public class B:A
  {
    public override int m(int a,int b)
    {
      return a-b;
     }
}
public class C:B
  {
   Public override int m(int x,int y)
    {
       return 2*(x-y);
     }
}
Note: output will be come like(?)