class Student:
    
    def __init__(self, first_name, last_name, grades=[]):
        self.first_name = first_name
        self.last_name = last_name
        self.grades = grades

    @property
    def full_name(self):
        return f'{self.first_name} {self.last_name}'

    @property
    def email(self):
        return f'{self.first_name}{self.last_name[0]}@codewars.com'

    @property
    def grade_average(self):
        return sum(self.grades) / len(self.grades)
    
    @property
    def basic_grades(self):
        return (('A', 90), ('B', 80), ('C', 70), ('D', 65))

    def assess(self):
        avg = self.grade_average
        for grade in self.basic_grades:
            if avg >= grade[1]:
                return grade[0]
        return 'F'