using System;

​

public class Program

{

    public static void Main()

    {

        Parent p1 = new Parent("yosi", "099999999");

        Student s1 = new Student("Bob", "000000000", p1);

        Parent p2 = new Parent("yosi", "099999999");

        Student s2 = new Student("Bob", "000000000", p2);

        Parent p3 = new Parent("yosi", "099999999");

        Student s3 = new Student("Bob", "000000000", p3);

        StudentList stList = new StudentList();  

        stList.Add(s1);

    }

}

​

//Parent

public class Parent

{

    private string name;

    private string cellNum;

    public Parent(string name, string cellNum)

    {

        this.name = name;

        this.cellNum = cellNum;

    }

​

    public string GetName()

    {

        return this.name;

    }

​

    public string GetCellNum()

    {

        return this.cellNum;

    }

​

    public void SetCellNum(string newCellNum)

    {

        this.cellNum = newCellNum;

    }

}

​

//Student

public class Student

{

    private string name;

    private string phoneNum;

    private Parent parent;

    public Student(string name, string phoneNum, Parent parent)

    {

        this.name = name;

        this.phoneNum = phoneNum;

        this.parent = parent;

    }

​

    public Student(Student st)

    {

        this.name = st.name;

        this.phoneNum = st.phoneNum;

        this.parent = st.parent;

    }

​

    public string GetName()

    {

        return this.name;

    }

​

    public string GetPhoneNum()

    {

        return this.phoneNum;

    }

​

    public void SetPhoneNum(string phoneNum)

    {

        this.phoneNum = phoneNum;

    }

​

    public Parent GetParent()

    {

        return this.parent;

    }

​

    public override string ToString()

    {

        return (this.name + " ," + this.phoneNum + "\n");

    }

}

​

//StudentList

public class StudentList

{

    public const int MAX_STUDENTS = 35;

    public int lastPosition;

    private Student[] list;

    public StudentList()

    {

        this.list = new Student[MAX_STUDENTS];

        this.lastPosition = 0;

    }

​

    private int FindStudent(string name)

    {

        int i;

        for (i = 0; i < this.lastPosition; i++)

        {

            if (this.list[i].GetName() == name)

                return i;

        }

​

        return -1;

    }

​

    private void MoveOthersBack(int k)

    {

        for (int i = k + 1; i < this.lastPosition; i++)

            this.list[i - 1] = this.list[i];

        this.lastPosition--;

    }

​

    private void MoveOthersForward(int k)

    {

        int j;

        for (j = this.lastPosition; j > k; j--)

            this.list[j] = list[j - 1];

        this.lastPosition++;

    }

    public void Add(Student st)

    {

        this.list[lastPosition++] = st;

        this.lastPosition++;

    }

    public string Del(string name, StudentList list)

    {

        if(list.FindStudent(name) == -1)

            return "null";

        else 

            return name;

        list.MoveOthersBack(lastPosition)

;           

    }

}