Letters Change Numbers

from string import ascii_uppercase
strings = input().split()

total_result = 0
for sub_string in strings:
    first_letter = sub_string[0]
    last_letter = sub_string[-1]
    number = int(sub_string[1:len(sub_string) - 1])

    first_letter_alphabet_position = ascii_uppercase.index(first_letter.upper()) + 1
    if first_letter.isupper():
        number /= first_letter_alphabet_position
    else:
        number *= first_letter_alphabet_position

    last_letter_alphabet_position = ascii_uppercase.index(last_letter.upper()) + 1
    if last_letter.isupper():
        number -= last_letter_alphabet_position
    else:
        number += last_letter_alphabet_position

    total_result += number

print(f"{total_result:.2f}")