public class Student
{

    private static int nextStudentId = 1;
    public string Name { get; set; }
    public int StudentId { get; set; }
    public int NumberOfCredits { get; set; }
    public double Gpa { get; set; }

    public Student(string name, int studentId,
            int numberOfCredits, double gpa)
    {
        Name = name;
        StudentId = studentId;
        NumberOfCredits = numberOfCredits;
        Gpa = gpa;
    }

    public Student(string name, int studentId)
        : this(name, studentId, 0, 0) {}

    public Student(string name)
        : this(name, nextStudentId)
    {
        nextStudentId++;
    }

    public void AddGrade(int courseCredits, double grade)
    {
        // Update the appropriate properties: NumberOfCredits, Gpa
    }

    public string GetGradeLevel()
    {
        // Determine the grade level of the student based on NumberOfCredits
    }

}