def vowelCount(s: str) -> int:
    """Count the number of vowels (a, e, i, o, u) in a string."""
    s = s.lower()
    return s.count("a") + s.count("e") + s.count("i") + s.count("o") + s.count("u")


print("Testing vowelCount()...", end="")
assert vowelCount("Abc def!!! a? yzyzyz!") == 3
assert vowelCount("Hi! How are you?") == 6
assert vowelCount("AAAEEEiOL") == 8
assert vowelCount("Rhythm") == 0
assert vowelCount("WHY, TRY SHY FLY RHYTHMS SLYLY.") == 0
print("Passed!")