D

n = int(input())
balls = [0]*501
user = {}
countUser = 0
for _ in range(n):
    query = input().split()
    if query[0] == 'ACHIEVE':
        try:
            user[int(query[1])] += 0
            balls[user[int(query[1])]] -= 1
        except:
            countUser += 1
        user[int(query[1])] = int(query[2])
        balls[int(query[2])] += 1
    elif query[0] == 'RATING':
        try:
            print("%.6f" % ((sum(balls[:user[int(query[1])]]))/(countUser-1)))
        except:
            try:
                balls[user[int(query[1])]] += 0
                print('1.000000')
            except:
                print('0.000000')