using System;

​

class A

{ protected double a;

 protected double b;

 public A(double a, double b)

 {this.a=a;

  this.b=b;

 }

 public void Info()

 {Console.WriteLine("a={0}    b={1}", a,b);

 }

 public double Sum()

 {return a+b;

 }

 public double Pr()

 {return a*b;

 }

}

class B:A

{ private double c;

public B(double a, double b,double c):base(a,b)

{this.c=c;

}

 public void Info1()

 {Console.WriteLine("a={0}    b={1}   c={2}", a,b,c);

 }

public double Sum1()

 {return a+b+c;

 }

 public double Pr1()

 {return a*b*c;

 }

​

}

public class Program

{

    public static void Main()

    {

        A a=new A(10,20);

        a.Info();

        Console.WriteLine("Suma={0}   Proizv={1}", a.Sum(), a.Pr() );

        B b=new B(10,20,30);

        b.Info1();

        Console.WriteLine("Suma={0}   Proizv={1}", b.Sum1(), b.Pr1() );

    }

}