{"raw_statement":[{"iden":"problem statement","content":"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."},{"iden":"constraints","content":"*   $2 \\leq N \\leq 100$\n*   $|S| = N$\n*   $S$ consists of lowercase English letters."},{"iden":"input","content":"Input is given from Standard Input in the following format:\n\n$N$\n$S$"},{"iden":"sample input 1","content":"6\naabbca"},{"iden":"sample output 1","content":"2\n\nIf 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 $2$."},{"iden":"sample input 2","content":"10\naaaaaaaaaa"},{"iden":"sample output 2","content":"1\n\nHowever we divide $S$, only `a` will be contained in both $X$ and $Y$."},{"iden":"sample input 3","content":"45\ntgxgdqkyjzhyputjjtllptdfxocrylqfqjynmfbfucbir"},{"iden":"sample output 3","content":"9"}],"translated_statement":null,"sample_group":[],"show_order":["default"],"formal_statement":null,"simple_statement":null,"has_page_source":true}