static void DeleteStudent(ref Laboratory laboratory)
{
List <Student> students = laboratory.GetStudents();
int deleteIndex = ChoiceStudent(ref students);
students.RemoveAt(--deleteIndex);
}
static void AddGrade(ref Laboratory laboratory)
{
List <Student> students = laboratory.GetStudents();
int choiceIndex = ChoiceStudent(ref students);
Student student = students.ElementAt(--choiceIndex);
Console.Clear();
Console.Write("Введите новую оценку для ID:{0}: ", student.Id);
student.AddGrade(Int32.Parse(Console.ReadLine()));
}
