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B. Polycarp and Letters

time limit per test

2 secondsmemory limit per test

256 megabytesinput

standard inputoutput

standard outputPolycarp loves lowercase letters and dislikes uppercase ones. Once he got a string *s* consisting only of lowercase and uppercase Latin letters.

Let *A* be a set of positions in the string. Let's call it pretty if following conditions are met:

- letters on positions from
*A*in the string are all distinct and lowercase; - there are no uppercase letters in the string which are situated between positions from
*A*(i.e. there is no such*j*that*s*[*j*] is an uppercase letter, and*a*_{1}<*j*<*a*_{2}for some*a*_{1}and*a*_{2}from*A*).

Write a program that will determine the maximum number of elements in a pretty set of positions.

Input

The first line contains a single integer *n* (1 ≤ *n* ≤ 200) — length of string *s*.

The second line contains a string *s* consisting of lowercase and uppercase Latin letters.

Output

Print maximum number of elements in pretty set of positions for string *s*.

Examples

Input

11

aaaaBaabAbA

Output

2

Input

12

zACaAbbaazzC

Output

3

Input

3

ABC

Output

0

Note

In the first example the desired positions might be 6 and 8 or 7 and 8. Positions 6 and 7 contain letters 'a', position 8 contains letter 'b'. The pair of positions 1 and 8 is not suitable because there is an uppercase letter 'B' between these position.

In the second example desired positions can be 7, 8 and 11. There are other ways to choose pretty set consisting of three elements.

In the third example the given string *s* does not contain any lowercase letters, so the answer is 0.

Codeforces (c) Copyright 2010-2019 Mike Mirzayanov

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