using System;
using static System.Console;

namespace Multilevel_Inheritance
{
   class classA
   {
       public int a = 10;
       public int total = 0;
       public void FunA()
       {
           WriteLine($"Value of a is {a}");
           WriteLine($"Total is {total}");
       }
   }
   
   class classB:classA
   {
       public int b = 20;
       public void FunB()
       {
       total = a + b;
           WriteLine($"Value of a is {a}");
           WriteLine($"Value of b is {b}");
           WriteLine($"Total is {total}");
       }
   }
   
   class classC:classB
   {
       public int c = 30;
       public void FunC()
       {
           total = a + b + c;
                WriteLine($"Value of a is {a}");
           WriteLine($"Value of b is {b}");
           WriteLine($"Value of c is {c}");
           WriteLine($"Total is {total}");
       }
   }
   
   class MultilevelInheritance
   {
       public static void Main(string[] args)
       {
           classA a = new classA();
           classB b = new classB();
           classC c = new classC();
           c.FunA();
           c.FunB();
           c.FunC();
       }
   }
}
\Playground\

One of my old C# codes
