Student Academy

students = {}

n = int(input())

for i in range(n):
    student = input()
    grade = float(input())

    if student not in students:
        students[student] = [grade, 1]
    else:
        students[student][0] += grade
        students[student][1] += 1

for student in students:
    students[student] = students[student][0] / students[student][1]

new = sorted(students, key=lambda x: students[x], reverse=True)

[print(f'{x} -> {students[x]:.2f}') for x in new if students[x] >= 4.5]