Problem Description

Two strings $a$ and $b$, both of length $m$, are called isomorphic if and only if:

• For any $1 \le i,j \le m$, if $a_i=a_j$, then $b_i=b_j$; otherwise, $b_i \ne b_j$.

Given two strings $s$ and $t$, both of length $n$. Among all strings $s'$ that are isomorphic to $s$, find the maximum number of pairs of identical characters at the same positions between $s'$ and $t$.

Input Format

This problem contains multiple test cases.

The first line of the input contains a positive integer $T$, indicating the number of test cases.

Then, the $T$ test cases follow sequentially. For each test case:

• The first line contains a single positive integer $n$.
• The second line contains a string $s$ of length $n$.
• The third line contains a string $t$ of length $n$.

Output Format

For each test case, output a single line containing an integer, representing the maximum number of pairs of identical characters at the same positions between $s'$ and $t$.

2
6
112233
221111
10
1234512345
1122334455

4
5

Hint

Explanation for Sample #1

For the first test case, we can have $s'=\texttt{221133}$, and the number of pairs of identical characters at the same positions between it and $t=\texttt{221111}$ is $4$. It can be proven that this is the maximum number.

For the second test case, we can have $s'=\texttt{1425314253}$, and the number of pairs of identical characters at the same positions between it and $t=\texttt{1122334455}$ is $5$. It can be proven that this is the maximum number.

Data Range

This problem uses bundled subtasks.

For all test cases, it is guaranteed that $1 \le T \le 5$, $1 \le n \le 10^5$, and both $s$ and $t$ consist only of numeric characters.

::cute-table{tuack}

• Special Property A: Both $s$ and $t$ consist only of $\texttt{0},\texttt{1},\texttt{2},\texttt{3},\texttt{4}$.