Polycarp 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 $*s*$.

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 $0$.