We’re preparing your current view and syncing the latest data.
Appleman has a string consisting of n lowercase English letters. For his task, he assigns an integer score to each unique character which is equal to the number of times this character occurs in the string. The problem is to determine the sum of scores of all unique characters in the string, where the score for each character is the number of its occurrences.
The first line contains integer n (1 ≤ n ≤ 100). The second line contains the string s of length n consisting of lowercase English letters.
Print a single integer — the sum of the scores of all unique characters in the string.
1 ≤ n ≤ 100 s consists of lowercase English letters only.
Example 1
Input
7 abacaba
Output
7
Explanation
Character counts: a=4, b=2, c=1, sum=7.