using System;

public class Program

{

    public static void Main()

    {

        var examen = new Test() {

            Profesor = new Prof() {

            Name = "Florin",

            }

        };

        UpdateTest(examen); 

        Console.WriteLine(examen);

    }

    static void UpdateTest(Test examen)

    {

        var update = examen;

        update.Profesor = new Prof {

                Materie = new Materie {

                    Name = "Florin"

                }

            };

    }

    private class Test

    {

        public Prof Profesor {get;set;}

    }

    private class Prof 

    {

        public string Name{get;set;}

        public Materie Materie{get;set;}

    }

    private class Materie 

    {

        public string Name{get;set;}

    }

}