using System;

using System.IO;

public class Program

{

    public static void Main()

    {

        try {

            InternalMethod();

        } catch (InvalidOperationException) 

        {

            //error handling

        } catch (Exception)

        {

            // nothing to do here

        }

    }

    public static void InternalMethod()

    {

            try{

                InvalidRequest();

            } catch(InvalidOperationException) 

            {

                throw new InvalidOperationException();

            } catch(FileNotFoundException) 

            {

                throw new InvalidOperationException(); //we do not want to catch other exceptions. Only InvalidOperationException regardless of exception thrown.

            }

    }

    public static void InvalidRequest() // external API

    {

            Random rnd = new Random(); // simulate multiple random exception but with the same handling

            if(rnd.Next(2) == 1){

                throw new InvalidOperationException(); 

            }

            else 

            {

                throw new FileNotFoundException();

            }

    }

}