I have a program which contains JuniorStudents and SeniorStudents. I've made seperate classes and in each class there is a list. Now when the student is year 6 or year 7 I shall promote it to senior student. I am doing this in the PromoteStudent method but when I call the ViewStudent method the SeniorStudent class I'm not getting the item. Can someone help me please? Here is the code:

Code:
public class JuniorStudentsClass
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    {
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   public List<Student> mystudent = new List<Student>();
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ublic void Addstudent()
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        {
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            Console.Write("enter students id:");
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            s.Id = Int32.Parse(Console.ReadLine());
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            Console.Write("enter students year:");
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            s.Year = Int32.Parse(Console.ReadLine());
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            Console.Write("enter name:");
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            s.Name = Console.ReadLine();
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            Console.Write("enter surname:");
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            s.Surname = Console.ReadLine();
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            Console.Write("enter dob:");
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            s.DOB = Console.ReadLine();
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            Console.Write("enter address:");
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            s.Addr = Console.ReadLine();
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            mystudent.Add(new Student(s.Id, s.Year, s.Name, s.Surname, s.DOB, s.Addr));
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        }
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 public void PromoteStudents(int index)
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        {
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            SearchItem(index);
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            Console.WriteLine("current record:");
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            Console.WriteLine("id is:" + mystudent[index].Id);
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            Console.WriteLine("year is:" + mystudent[index].Year);
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            Console.WriteLine("name is:" + mystudent[index].Name);
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            Console.WriteLine("surname is:" + mystudent[index].Surname);
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            Console.WriteLine("dob is:" + mystudent[index].DOB);
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            Console.WriteLine("address is:" + mystudent[index].Addr);
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            Console.WriteLine("enter new year of student to promote");
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            s.Year = Int16.Parse(Console.ReadLine());
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            if (((s.Year == 7)) || ((s.Year == 8)))
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            {              
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                sc.List.Add(new Student(mystudent[index].Id, s.Year, mystudent[index].Name, mystudent[index].Surname, mystudent[index].DOB, mystudent[index].Addr));
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                Console.WriteLine("student promoted to senior student");
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            }
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            else
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            {
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                mystudent.Add(new Student(mystudent[index].Id, s.Year, mystudent[index].Name, mystudent[index].Surname, mystudent[index].DOB, mystudent[index].Addr));
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                Console.WriteLine("student promoted to next year");
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            }
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        }
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045
 
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        public int SearchItem(int search)
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        {
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            int found = -1;
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            if (mystudent != null)
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            {
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                foreach (Student st in mystudent)
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                {
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                    found++;
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                    if (Student.Equals(search, st))
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                    {
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                        break;
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                    }
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                }
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            }
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            return found;
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        }
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public class SeniorStudentsClass
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    {
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        Student s = new Student();;
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        public List<Student> studlist = new List<Student>();
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        public List<Student> List {
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            get { return studlist; }
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            set { studlist = value; }
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        }
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        public void Addstudent()
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        {
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            Console.Write("enter students id:");
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            s.Id = Int32.Parse(Console.ReadLine());
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            Console.Write("enter students year:");
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            s.Year = Int32.Parse(Console.ReadLine());
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            Console.Write("enter name:");
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            s.Name = Console.ReadLine();
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            Console.Write("enter surname:");
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            s.Surname = Console.ReadLine();
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            Console.Write("enter dob:");
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            s.DOB = Console.ReadLine();
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            Console.Write("enter address:");
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            s.Addr = Console.ReadLine();
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            studlist.Add(new Student(s.Id, s.Year, s.Name, s.Surname, s.DOB, s.Addr));  
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        }  public void ViewStudents()
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        {
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            for (int i = 0; i < studlist.Count; i++)
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            {
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                Console.Write(studlist[i].Id + "\t");
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                Console.Write(studlist[i].Year + "\t");
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                Console.Write(studlist[i].Name + "\t");
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                Console.Write(studlist[i].Surname + "\t");
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                Console.Write(studlist[i].DOB + "\t");
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                Console.Write(studlist[i].Addr);
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                Console.WriteLine();
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            }
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        }
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  public class Student
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    {
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        Marks mrk = new Marks();
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        private int id;
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        private string name;
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        private string surname;
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        private string dob;
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        private string address;
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        private int year;
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        public Student()
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        {
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        }
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        public Student(int id, int yr,string name, string surname, string dob, string address)
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        {
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            this.id = id;
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            this.name = name;
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            this.surname = surname;
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            this.dob = dob;
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            this.address = address;
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            this.year = yr;
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        }
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      public string Name
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        {
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            get { return name; }
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            set { name = value; }
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        }
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        public string Surname
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        {
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            get { return surname; }
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            set { surname = value; }
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        }
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        public string DOB
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        {
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            get { return dob; }
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            set { dob = value; }
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        }
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        public string Addr
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        {
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            get { return address; }
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            set { address = value; }
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        }
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        public int Id
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        {
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            get { return id; }
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            set { id = value; }
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        }
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159
 
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        public int Year
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        {
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            get { return year; }
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            set { year = value; }
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165
        }