class Mentor():
    def __init__(self, aName, *allStudents):
        allStudents = list(allStudents)
        self._students = None
        self._name = None
        self._name = aName
        self._students = []
        didAddStudents = self.setStudents(*allStudents)
        if not didAddStudents :
            raise RuntimeError ("Unable to create Mentor, must have 4 students. See http://manual.umple.org?RE002ViolationofAssociationMultiplicity.html")

    def setName(self, aName):
        wasSet = False
        self._name = aName
        wasSet = True
        return wasSet

    def getName(self):
        return self._name

    def getStudent(self, index):
        aStudent = self._students[index]
        return aStudent

    def getStudents(self):
        newStudents = tuple(self._students)
        return newStudents

    def numberOfStudents(self):
        number = len(self._students)
        return number

    def hasStudents(self):
        has = len(self._students) > 0
        return has

    def indexOfStudent(self, aStudent):
        index = (-1 if not aStudent in self._students else self._students.index(aStudent))
        return index

    @staticmethod
    def requiredNumberOfStudents():
        return 4

    @staticmethod
    def minimumNumberOfStudents():
        return 4

    @staticmethod
    def maximumNumberOfStudents():
        return 4

    def setStudents(self, *newStudents):
        newStudents = list(newStudents)
        wasSet = False
        verifiedStudents = []
        for aStudent in newStudents:
            if (aStudent) in verifiedStudents :
                continue
            verifiedStudents.append(aStudent)

        if len(verifiedStudents) != len(newStudents) or len(verifiedStudents) != Mentor.requiredNumberOfStudents() :
            return wasSet
        self._students.clear()
        self._students.extend(verifiedStudents)
        wasSet = True
        return wasSet

    def delete(self):
        self._students.clear()

    def __str__(self):
        return str(super().__str__()) + "[" + "name" + ":" + str(self.getName()) + "]"


class Student():
    def __init__(self, aNumber):
        self._number = None
        self._number = aNumber

    def setNumber(self, aNumber):
        wasSet = False
        self._number = aNumber
        wasSet = True
        return wasSet

    def getNumber(self):
        return self._number

    def delete(self):
        pass

    def __str__(self):
        return str(super().__str__()) + "[" + "number" + ":" + str(self.getNumber()) + "]"