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CF1890B.Qingshan Loves Strings
Qingshan Loves Strings
Qingshan has a string , while Daniel has a string . Both strings only contain 0 and 1.
A string of length is good if and only if
- for all .
For example, 1, 101, 0101 are good, while 11, 1001, 001100 are not good.
Qingshan wants to make good. To do this, she can do the following operation any number of times (possibly, zero):
- insert to any position of (getting a new ).
Please tell Qingshan if it is possible to make good.
Input
The input consists of multiple test cases. The first line contains a single integer () — the number of test cases. The description of the test cases follows.
The first line of each test case contains two integers and () — the length of the strings and , respectively.
The second line of each test case contains a string of length .
The third line of each test case contains a string of length .
It is guaranteed that and only contain 0 and 1.
Output
For each test case, print "YES" (without quotes), if it is possible to make good, and "NO" (without quotes) otherwise.
You can print letters in any case (upper or lower).
Note
In the first test case, is good initially, so you can get a good by doing zero operations.
In the second test case, you can do the following two operations (the inserted string is underlined):
1}\underline{\texttt{010}}\texttt{1110101}\underline{\texttt{010}}\texttt{1
and get , which is good.
In the third test case, there is no way to make good after any number of operations.
Samples
5
1 1
1
0
3 3
111
010
3 2
111
00
6 7
101100
1010101
10 2
1001001000
10
Yes
Yes
No
No
No
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