Given a string, count the number of vowels it contains. Vowels are defined as a, e, i, o, u (both uppercase and lowercase).

Examples

Example 1

Input:  "hello"
Output: 2

Contains 'e' and 'o'

Example 2

Input:  "PROGRAMMING"
Output: 3

Contains 'O', 'A', and 'I'

Constraints

• Case-insensitive vowel counting
• String can be empty