题解 | #牛牛的绩点#

import sys

grade = []
d = {'A':4.0,'B':3.0,'C':2.0,'D':1.0,'F':0.0}

for line in sys.stdin:
    a = line.split()
    
    if a != ['False']:
        grade.append(a[0])

sum=0
s1 = 0
for i in range(0,len(grade),2):
    # print(i)
    sum += d[grade[i]]*eval(grade[i+1])
    s1 += eval(grade[i+1])

print('%.2f'%(sum/s1))