using System;

public class Program

{

    public static void Main()

    {

        Student std = new Student();

        std.age = 10;

        Console.WriteLine(std.age);

        Student std2 = new Student(21);

        Console.WriteLine(std.age2);

    }

}

class Student

{

    public int age

    {

    get;

    set;

    }

    public int age2

    {

    get;

    private set;

    }

    public Student()

    {

    }

    public Student(int a)

    {

    age =a;

    }

}