//3.
        public int CompareTo(Student other)
        {
            if (this.FirstName.CompareTo(other.FirstName) != 0)
            {
                return this.FirstName.CompareTo(other.FirstName);
            }
            if (this.MiddleName.CompareTo(other.MiddleName) != 0)
            {
                return this.MiddleName.CompareTo(other.MiddleName);
            }
            if (this.LastName.CompareTo(other.LastName) != 0)
            {
                return this.LastName.CompareTo(other.LastName);
            }
            if (this.Ssn.CompareTo(other.Ssn) != 0)
            {
                return this.Ssn.CompareTo(other.Ssn);
            }
            return 0;
        }



        public int CompareTo(Object obj)
        {
            if (obj != null && !(obj is Student))
            {
                throw new ArgumentException("Object must be of type Student.");
            }

            return CompareTo(obj as Student);
        }