using System;

public class Professor

{

    public string professorName;

​

    private int _iAge;

    public int iAge

    {

        get

        {

            return _iAge;

        }

        set

        {

            if (value < 18 || value > 70)

            {

                _iAge = 30;

            }

            else 

            {

                _iAge = value;

            }

        }

    }

    public Professor()

    {

    }

}

public class Program

{

    public static void Main()

    {   

        Professor professor1 = new Professor();

        professor1.professorName = "Liu";

        professor1.iAge = 99;

        Console.WriteLine(professor1.professorName);

        Console.WriteLine(professor1.iAge);

    }

}