CF1704A Two 0-1 Sequences

AquaMoon has two binary sequences $ a $ and $ b $ , which contain only $ 0 $ and $ 1 $ . AquaMoon can perform the following two operations any number of times ( $ a_1 $ is the first element of $ a $ , $ a_2 $ is the second element of $ a $ , and so on): - Operation 1: if $ a $ contains at least two elements, change $ a_2 $ to $ \operatorname{min}(a_1,a_2) $ , and remove the first element of $ a $ . - Operation 2: if $ a $ contains at least two elements, change $ a_2 $ to $ \operatorname{max}(a_1,a_2) $ , and remove the first element of $ a $ . Note that after a removal of the first element of $ a $ , the former $ a_2 $ becomes the first element of $ a $ , the former $ a_3 $ becomes the second element of $ a $ and so on, and the length of $ a $ reduces by one. Determine if AquaMoon can make $ a $ equal to $ b $ by using these operations.

The first line contains a single integer $ t $ ( $ 1 \leq t \leq 2\,000 $ ) — the number of test cases. Description of test cases follows. The first line of each test case contains two integers $ n $ , $ m $ ( $ 1 \leq n,m \leq 50 $ , $ m \leq n $ ) — the lengths of $ a $ and $ b $ respectively. The second line of each test case contains a string $ a $ of length $ n $ , consisting only $ 0 $ and $ 1 $ . The third line of each test case contains a string $ b $ of length $ m $ , consisting only $ 0 $ and $ 1 $ .

For each test case, output "YES" if AquaMoon can change $ a $ to $ b $ by using these options; otherwise, output "NO". You may print each letter in any case (for example, "YES", "Yes", "yes", "yEs" will all be recognized as a positive answer).

In the first test case, you can use Operation 2 four times to make $ a $ equals to $ b $ . In the second test case, you can use Operation 1 four times to make $ a $ equals to $ b $ . In the third test case, it can be proved that no matter how we use the operations, it is impossible to make $ a $ equal to $ b $ . In the fourth test case, it can be proved that no matter how we use the operations, it is impossible to make $ a $ equal to $ b $ . In the fifth test case, you can use Operation 2 three times to make $ a $ become $ 10101 $ , so the first element of $ a $ equals to the first element of $ b $ , but it can be proved that no matter how to operate, the second to the fifth elements of $ a $ can't be the same as $ b $ .