Contest Duration: - (local time) (100 minutes) Back to Home
B - Cut and Count /

Time Limit: 2 sec / Memory Limit: 1024 MB

### 制約

• 2 \leq N \leq 100
• |S| = N
• S は英小文字からなる

N
S

### 出力

XY のどちらにも含まれている文字」の種類数の最大値を出力せよ。

6
aabbca

### 出力例 1

2

S を先頭から 3 文字目と 4 文字目の間で切って X = aabY = bca に分割すると、「XY のどちらにも含まれている文字」は ab です。 「XY のどちらにも含まれている文字」の種類数が 3 以上になることはないので、答えは 2 になります。

10
aaaaaaaaaa

### 出力例 2

1

どのように S を分割しても、「XY のどちらにも含まれている文字」は a のみです。

### 入力例 3

45
tgxgdqkyjzhyputjjtllptdfxocrylqfqjynmfbfucbir

### 出力例 3

9

Score : 200 points

### Problem Statement

You are given a string S of length N consisting of lowercase English letters. We will cut this string at one position into two strings X and Y. Here, we would like to maximize the number of different letters contained in both X and Y. Find the largest possible number of different letters contained in both X and Y when we cut the string at the optimal position.

### Constraints

• 2 \leq N \leq 100
• |S| = N
• S consists of lowercase English letters.

### Input

Input is given from Standard Input in the following format:

N
S

### Output

Print the largest possible number of different letters contained in both X and Y.

6
aabbca

### Sample Output 1

2

If we cut the string between the third and fourth letters into X = aab and Y = bca, the letters contained in both X and Y are a and b. There will never be three or more different letters contained in both X and Y, so the answer is 2.

10
aaaaaaaaaa

### Sample Output 2

1

However we divide S, only a will be contained in both X and Y.

### Sample Input 3

45
tgxgdqkyjzhyputjjtllptdfxocrylqfqjynmfbfucbir

9