Count Vowels
Given a string, count how many vowels it contains.
Input
A single line containing a string s of 1 to 10^5 ASCII characters (letters, digits, spaces and punctuation).
Output
A single integer: the number of vowels (a, e, i, o, u, case-insensitive) in s.
Examples
Input: hello
Output: 2
Input: Python
Output: 1
Input: AEIOU
Output: 5
Input: xyz
Output: 0
No vowels at all is a valid case: the count is simply 0.