using System;
abstract class M1
{
public int add(int a,int b)
return (a+b);
}
class M2:M1
public int mul(int a, int b)
return (a*b);
public class Program
public static void Main()
M2 ob=new M2();
int result = ob.add(10,20);
int resultm = ob.mul(10,20);
Console.WriteLine(result);
Console.WriteLine(resultm);
Console.ReadLine();
//Console.WriteLine("Hello World");