Lonely Y loves his string of lowercase letters, Y is about to escape so he should choose just one lowercase letter and carry all letters in which is equal to with himself.
What is the maximum number of letters Y can carry with himself?
Input
First line contains only , legnth of string .
Second line contains string of lowercase letters.
Output
The only line of output contains an integer which is maximum number of letters that Y can carry.
Y can choose letter and carry characters of .