def solution(roman_numerals_filename: str = "/p089_roman.txt") -> int:

    savings = 0

    with open(os.path.dirname(__file__) + roman_numerals_filename) as file1:
        lines = file1.readlines()

    for line in lines:
        original = line.strip()
        num = parse_roman_numerals(original)
        shortened = generate_roman_numerals(num)
        savings += len(original) - len(shortened)

    return savings