786. Exploring Good Strings
A Good String is defined as a string that consists solely of vowels (a, e, i, o, u). Given a string S, determine the length of the longest substring of S that is also a Good String and output it as a positive integer N. **Note**: The time limit for this problem is 1 second, so it is important to optimize the substring computation.
A string 'S' representing the input string.
A single positive integer N representing the length of the longest substring of S that is also a Good String.
String length < 10^5