class Student(Person):
    #   Class Constructor
    #   
    #   Parameters:
    #   firstName - A string denoting the Person's first name.
    #   lastName - A string denoting the Person's last name.
    #   id - An integer denoting the Person's ID number.
    #   scores - An array of integers denoting the Person's test scores.
    #
    # Write your constructor here
    def __init__(self, firstName, lastName, idNumber, scores):
        Person.__init__(self,firstName, lastName, idNumber)
        self.scores = scores

#   Function Name: calculate
#   Return: A character denoting the grade.
#
# Write your function here
def calculate(self):
    sum = 0
    for i in range(len(self.scores)):
        sum = sum + self.scores[i]

        avg = sum/len(self.scores)

    if ((90<=avg) and (avg<=100)):
        return str("O")
    elif ((80<=avg) and (avg<90)):
        return str("E")
    elif ((70<=avg) and (avg<80)):
        return str("A")
    elif ((55<=avg) and (avg<70)):
        return str("P")
    elif ((40<=avg) and (avg<55)):
        return str("D")
    else:
        return str("T")