Description:
Qingshan has a string $$$s$$$, while Daniel has a string $$$t$$$. Both strings only contain $$$\texttt{0}$$$ and $$$\texttt{1}$$$.
A string $$$a$$$ of length $$$k$$$ is good if and only if
- $$$a_i \ne a_{i+1}$$$ for all $$$i=1,2,\ldots,k-1$$$.
For example, $$$\texttt{1}$$$, $$$\texttt{101}$$$, $$$\texttt{0101}$$$ are good, while $$$\texttt{11}$$$, $$$\texttt{1001}$$$, $$$\texttt{001100}$$$ are not good.
Qingshan wants to make $$$s$$$ good. To do this, she can do the following operation any number of times (possibly, zero):
- insert $$$t$$$ to any position of $$$s$$$ (getting a new $$$s$$$).
Please tell Qingshan if it is possible to make $$$s$$$ good.
Input Format:
The input consists of multiple test cases. The first line contains a single integer $$$T$$$ ($$$1\le T\le 2000$$$) — the number of test cases. The description of the test cases follows.
The first line of each test case contains two integers $$$n$$$ and $$$m$$$ ($$$1 \le n,m \le 50$$$) — the length of the strings $$$s$$$ and $$$t$$$, respectively.
The second line of each test case contains a string $$$s$$$ of length $$$n$$$.
The third line of each test case contains a string $$$t$$$ of length $$$m$$$.
It is guaranteed that $$$s$$$ and $$$t$$$ only contain $$$\texttt{0}$$$ and $$$\texttt{1}$$$.
Output Format:
For each test case, print "YES" (without quotes), if it is possible to make $$$s$$$ good, and "NO" (without quotes) otherwise.
You can print letters in any case (upper or lower).
Note:
In the first test case, $$$s$$$ is good initially, so you can get a good $$$s$$$ by doing zero operations.
In the second test case, you can do the following two operations (the inserted string $$$t$$$ is underlined):
1. $$$\texttt{1}\underline{\texttt{010}}\texttt{11}$$$
2. $$$\texttt{10101}\underline{\texttt{010}}\texttt{1}$$$
and get $$$s = \texttt{101010101}$$$, which is good.
In the third test case, there is no way to make $$$s$$$ good after any number of operations.