dict = {'A':4.0, 'B':3.0, 'C':2.0, 'D':1.0, 'F':0} grade_list = [] score_list = [] while True: x = input() if x == 'False': break else: y = int(input()) grade_list.append(dict[x]*y) score_list.append(y) averagescore = sum(grade_list) / sum(score_list) print('%.2f'%averagescore)