using System;

namespace Inheritance

{

public class Parent

{

    public int addition(int a,int b)

    {

        int c=a+b;

        return c;

    }

}

    public class Mid : Parent

{

    public string additions(string a,string b)

    {

        string res=a+" "+b;

        return res;

    }

}

public sealed class Program : Mid

{

    public static void Main()

    {

        Mid obj=new Mid();

        Console.WriteLine("enter the entities to be added");

        string inp1=Console.ReadLine();

        string inp2=Console.ReadLine();

        try

        {

        int a=Convert.ToInt32(inp1);

        int b=Convert.ToInt32(inp2);

            int c=obj.addition(a,b);

            Console.WriteLine("The sum of {0} and {1} is {2}",a,b,c);

        }

        catch(Exception e)

        {

            string res=obj.additions(inp1,inp2);

            Console.WriteLine("The concatenation of {0} and {1} is {2}",inp1,inp2,res);

        }

    }

}

​

}