You are given a string $S[1..N]$ containing only lowercase letters. Now you need to find the longest substring $S[l..r]$ such that every letter (`a` to `z`) appears no more than $K$ times in the substring. You just need to output the length ($r-l+1$) of the longest substring.
输入解释
There are multiple test cases.
Each test case contains one integer $K$ ($1\leq K \leq N$) and one string $S$ in one line.
It's guaranteed that the sum of lengths of the input strings is no more than $4 \times 10^5$.
输出解释
For each test case, print one integer in one line, denoting the length of the longest substring.