Функция принимает на вход ровно два символа. Функция возвращает 1, если каждый введенный символ является буквой или цифрой, и 0 в противном случае. Цифры — это арабские цифры от 0 до 9. Буквы — это латинский, кириллический или современный греческий

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TECHNICAL ENTRY TEST

Please solve the task before the interview and send requested test cases to us.

Function takes two and only two characters as input. It returns 1 when each entered symbol is either letter or number and 0 in other cases.
Numbers are Hindu-Arabic numerals from 0 to 9. Letters are Latin, Cyrillic or Modern Greek alphabet.

The bug was found before, slogan is: "Cyrillic letter can be treated as non-letter symbol"
Actions to reproduce:
Function input: Ay.
Expected output: 1. (Logic: only letters).
Observed output: 0 .

The bug was fixed. Existing tests were already ran as a regression test after bugfix, here is the test report:
\begin{tabular}{lll}
Input & Expected output & Status \\
AA & 1 & Passed \\
1A & 1 & Passed \\
11 & 1 & Passed \\
A\$ & 0 & Passed \\
1 & 0 & Passed
\end{tabular}

What tests cases will you do for bug's verification?
What tests cases will you propose to enforce regression testing of the function?
Negative tests like input less than 2 symbols and input more than 2 symbols are out of scope for both bug verification and additional regression test cases.
We will be glad to see your reasoning and argumentation as an addition, but the main thing is to provide test cases for both bug verification and additional regression test cases.
THANK YOU!