def complement(gender):
    if gender == "M":
        return "F"
    else:
        return "M"

def lastLetterIndex():
    # Open the file and extract all the information into
    # a giant list
    f = open("babyNames.txt", "r")
    L = []
    for line in f:
        L.append(line.strip().split(","))
    f.close()
    
    # Initialize dictionary
    D = {}
    # Each lower case letter is a key
    for ch in range(ord("a"), ord("z")+1):
        D[chr(ch)] = []
        # The value of each such key is a list of 
        # 134 dictionaries, initially empty
        for i in range(134):
            D[chr(ch)].append({})
            

    # Populate dictionary with elements from L
    for record in L:
        year = int(record[0])
        name = record[1]
        gender = record[2]
        freq = int(record[3])
        lastLetter = name[len(name)-1]
        
        if name not in D[lastLetter][year-1880]:
            D[lastLetter][year-1880][name] = [(gender, freq), (complement(gender), 0)]
            D[lastLetter][year-1880][name].sort()
        elif gender == "F":
            D[lastLetter][year-1880][name][0] = (gender, freq)
        else:
            D[lastLetter][year-1880][name][1] = (gender, freq)
            
    return D