def vowels(word):
    number_of_vowels = 0
    the_vowels = ["a", "e", "i", "o", "u"]
    for letter in word.lower():
        if letter in the_vowels:
            number_of_vowels += 1
    return number_of_vowels

word = "pneumonoultramicroscopicsilicovolcanoconiosis"
print(vowels(word))