def vocabulary(word_and_punctuation_instances, punctuation):
    '''word_and_punctuation_instances is a list of strings; punctuation is
    a list of punctuation characters. Return a new list that is the
    vocabulary of word_and_punctuation_instances, that is, all the distinct elements of
    word_and_punctuation_instances that are not in the punctuation list.
    By all the distinct elements, we mean the list returned does not include
    duplicates.'''
    
def analyze_vocabulary(word_and_punctuation_instances, punctuation):

    '''Determine and print the number of words in the vocabulary of
    word_and_punctuation_instances, as well as a sorted list of those
    words.  "punctuation" is a list of punctuation characters.  They
    may occur in word_and_punctuation_instances, but are not treated
    as words in the vocabulary.'''

    # note:  if v is a list, then v.sort() shorts the list and puts the 
    #        results back in v
    
def print_stats(word_and_punctuation_instances, within_sentence_punctuation, \
		end_sentence_punctuation):    
    '''"word_and_punctuation_instances" is a list of strings;
    "within_sentence_punctuation" and "end_sentence_punctionation" are
    lists of punctuation characters that can occur in the middle
    of a sentence, or at the end of a sentence, respectively.  Print
    statistics about the words, sentences, and readability of
    word_and_punctuation_instances (the print statements below
    tell you which statistics to calculate).  The float values 
    are printed to 2 decimal places.'''
    
    # Add code here to make your calculations.   

    # In each print statement below, replace the value 99 with an appropriate
    # expression.
    print("Number of distinct words:",99)
    print("Number of words:", 99)
    print("Average word length:", 99)
    print("Number of sentences:", 99)
    print("Average sentence length:", 99)
    print("ARI:", 99)

    
def separate_punctuation(strings, punctuation_list):
    '''strings is a list of strings.  "punctuation" is a list of 
    punctuation characters.  Return a new list that is the same as strings, 
    but for every string that ends in a punctuation character, the string 
    (without the punctuation) and the punctuation are separated and
    made two elements of the list.'''

    # suppose s is a string.  s[-1] is the last char of s, and s[:-1] is all
    #   but the last char of s.

def print_one_line(list):
    '''Print the strings in 'list' on a single line, with commas separating
    them.  '''

    # Make sure you do not print a comma after the last item!
  
def get_valid_command(valid):
    '''Prompt for and return a string that is a valid command, i.e., a string
    in the list "valid".'''
    
    # Uncomment out the following two lines and use them, as many times as 
    # needed, as your ONLY input and output in this function:
    
    #command = input("Please enter a command: ")
    #print("Invalid command")
    

def main():
    # Get the name of a file to analyze, and put its contents into a
    # list of strings.
    filename = input("File to analyze: ")
    f = open(filename, 'r')
    contents = f.read().split()
        
    # inner_punct is a list of within-sentence punctuation.
    # end_punct is a list of end-of-sentence punctuation.
    # punct is a list of all punctuation characters.
    inner_punct = [",", ";", "-"]
    end_punct = ["!", "?", "."]
    punct = inner_punct + end_punct
    
    # Separate any punctuation that is attached to the end of words.
    contents = separate_punctuation(contents, punct)
    
    # Tell the user what the valid commands are, then
    # read and process the user's command.
    valid_commands = ["stats", "vocab"]
    print ("The valid commands are:",end="") 
    print_one_line(valid_commands)
    command = get_valid_command(valid_commands)
    if command == "stats":
	print_stats(contents, inner_punct, end_punct)
    elif command == "vocab":
	analyze_vocabulary(contents, punct)

main()