题解 | #牛牛的绩点#

l1=[]
l2=[]
while(True):
    test=input('')
    if(test == 'A'):
        l1.append(4)
    elif(test == 'B'):
        l1.append(3)
    elif(test == 'C'):
        l1.append(2)
    elif(test == 'D'):
        l1.append(1)
    elif(test == 'F'):
        l1.append(0)
    elif(test == 'False'):
        break
    else:
        l2.append(int(test))
l3=[]
for i in range(0,len(l1),1):
    l3.append(l1[i]*l2[i])
print('%.2f'%(sum(l3)/sum(l2)))