Can you help me as my program isn't working if the string contains numbers as well as upper and lower case letters. he program is attached below and

Can you help me as my program isn't working if the string contains numbers as well as upper and lower case letters.

he program is attached below and is written in python 3.

def max_relative_frequency(s):

 # store uppercases and lowercases

 uppercases = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'

 lowercases = 'abcdefghijklmnopqrstuvwxyz'

 # generate a list of 26 values to store the frequency of each alphabet

 frequency = [0 for i in range(len(uppercases))]

 # check each character of the s

 for i in range(len(s)):

  # check for uppercase

  if s[i] in uppercases:

   frequency[uppercases.index(s[i])] += 1

  # check for lowercase

  elif s[i] in lowercases:

   frequency[lowercases.index(s[i])] += 1

 # find the maximum of the frequency

 maximum = max(frequency)

 # return the maximum frequency

 return maximum/(len(s)-s.count(' ')-s.count('.')-s.count(';')-s.count(','))