时间限制：C/C++/Rust/Pascal 4秒，其他语言8秒
空间限制：C/C++/Rust/Pascal 512 M，其他语言1024 M
64bit IO Format: %lld
空间限制：C/C++/Rust/Pascal 512 M，其他语言1024 M
64bit IO Format: %lld
题目描述
Two strings 
and 
are isomorphic if and only if k = l and there exists a injection 
such that )
for all 
.
Note that a function f is injection if and only if%20%5Cneq%20f(y))
for all 
.
Bobo would like to choose some strings from all%7D%7B2%7D)
substrings of the given string 
.
Find out the maximum number of strings he may choose so that no two chosen strings are isomorphic.
Note that a function f is injection if and only if
Bobo would like to choose some strings from all
Find out the maximum number of strings he may choose so that no two chosen strings are isomorphic.
输入描述:
The input consists of several test cases and is terminated by end-of-file.
The first line of each test case contains an integer n.
The second line contains a string.
*
*
* There are at mosttest cases, and at most 5 of them have n > 50.
输出描述:
For each test case, print an integer which denotes the result.