class Student
    {
        public int Id;
        public string Name;
    }
	
static DataTable GetDataTable(Student[] students)
        {
            DataTable table = new DataTable(); 
            table.Columns.Add("Id", typeof(Int32)); 
            table.Columns.Add("Name",typeof(string));
            foreach (Student student in students)
            {
                table.Rows.Add(student.Id, student.Name);
            }
            return (table);
        }	
		
void Main()
{
			Student[] students_a = {
									new Student { Id=1, Name="Александр Ерохин"},
									new Student { Id=5, Name="Елена Волкова"},
									new Student { Id=9, Name="Дмитрий Моисеенко"},
									new Student { Id=1, Name="Александр Ерохин"},
									new Student { Id=16, Name="Андрей Мухамедшин"},
									new Student { Id=20, Name="Ирина Сас"},
									new Student { Id=28, Name="Артем Амурин"}
                                 };
								 
			Student[] students_b = {
									new Student { Id=1, Name="Александр Ерохин"},
									new Student { Id=5, Name="Елена Волкова"},
									new Student { Id=100, Name="New Memeber"}
                                 };								 
								 

            DataTable dt_a = GetDataTable(students_a);	
            DataTable dt_b = GetDataTable(students_b);				
			
			dt_a.Dump("Before");
			
			var q_contains = dt_b.AsEnumerable().Where(b_row => !dt_a.AsEnumerable().Select(row_a => row_a.Field<Int32>("Id")).Contains(b_row.Field<Int32>("Id")) );
			
			q_contains.ToList<DataRow>().ForEach(new_one => dt_a.Rows.Add(new_one.Field<Int32>("Id"), new_one.Field<string>("Name")));
			
			dt_a.Dump("After");
			
			
}

// Define other methods and classes here