using System;

public class Program

{

    public static void Main()

    {

        Classroom c1=new Classroom("sex");

        Classroom c2=new Classroom("sex1");

        c1.AddStudent(new Student(1,"xxx",69));

        c1.AddStudent(new Student(2,"xxx1",70));

        c1.AddStudent(new Student(3,"xxx2",71));

        c2.AddStudent(new Student(4,"xnxx2",6));

        c2.AddStudent(new Student(5,"pornhub",7));

        c2.AddStudent(new Student(6,"pornhub1",8));

        c1.GetStudentCount();

        c1.RemoveStudent(2);

        c1.GetStudentCount();

    }

}

public class Student 

{

    private int ID;

    private string Name;

    private int age;

    public Student(int ID, string Name, int age)

    {

        this.ID = ID;

        this.Name = Name;

        this.age = age;

    }

    public void SetID(int ID)

    {

        this.ID = ID;

    }

    public void SetName(string Name)

    {

        this.Name = Name;

    }

    public void Setage(int age)

    {

        this.age = age;

    }

    public int GetID()

    {

        return this.ID;

    }

    public string GetName()

    {

        return this.Name;

    }

    public int Getage()

    {

        return this.age;

    }

}

public class Classroom

{

    private string className;

    private Student[] Students;

    private int counter;

    public Classroom(string className)

    {

        this.className=className;

        this.Students = new Student[5];

        this.counter=0;

    }

    public void AddStudent(Student s)

    {

        Students[counter]=s;

        counter++;

    }

    public void RemoveStudent(int ID)

    {

        for(int i=0;i<counter;i++)

        {

            if(Students[i].GetID()==ID)

            {

                for(int j=i;j<counter-1;j++)

                {

                    Students[j]=Students[j+1];

                }

                counter--;

            }

        }

    }

    public void GetStudentCount()

    {

        Console.WriteLine(counter);

    }

}