Student.cs

class Student : IEquatable<Student>
{
    public string Name { get; set; }
    public int Number { get; set; }
    public int SerialNo { get; set; }
    public int Grade { get; set; }

    public bool Equals(Student other)
    {
        if (other.SerialNo == SerialNo)
            return true;
        else
            return false;
    }

    public override bool Equals(object obj)
    {
        if (obj is Student student)
            return Equals(student);
        else
            return false;
    }

    public override int GetHashCode()
    {
        return SerialNo.GetHashCode();
    }
}