Question
Letter Limit
Kiran is given a string T of length M, composed of lowercase English letters. An alphabet set of size b (1 ≤ b ≤ 26) includes only the first b lowercase letters. Determine the smallest alphabet size needed to form T.
Input
The first line of the input contains a single integer M.
The second line of the input contains a string T.
The second line of the input contains a string T.
Output
Print the minimum alphabet size required so that you can write T.
Example
Sample Input
5
trees
Sample Output
20
Explanation
We need letters till the letter 't' in this English alphabet which is the 20th character.
5
trees
Sample Output
20
Explanation
We need letters till the letter 't' in this English alphabet which is the 20th character.