# Assume s is a string of lower case characters.
#
# Write a program that counts up the number of vowels contained in the string
# s. Valid vowels are: 'a', 'e', 'i', 'o', and 'u'. For example, if s =
# 'azcbobobegghakl', your program should print:
# Number of vowels: 5

vowels = 0
for letter in s:
    if letter == 'a' \
    or letter == 'e' \
    or letter == 'i' \
    or letter == 'o' \
    or letter == 'u':
        vowels += 1
print('Number of vowels:', str(vowels))
