using System;

public class Program

{

    public interface IPerson

    {

        string FullName { get; }

    }

    public class Person : IPerson

    {

        private string _firstName;

        private string _lastName;

        public string FullName => $"{_firstName} {_lastName}";

    }

    public class PersonViewModel

    {

        private readonly IPerson _person;

        // Here you can receive either Doctor, Worker, Mommy or whatever the class that implements IPerson interface

        public PersonViewModel(IPerson person)

        {

            _person = person;

        }

        public string FullNameWhateverTheName => _person.FullName;

    }

    public static void Main()

    {

        Console.WriteLine("Hello World");

    }

}