CF1915B Not Quite Latin Square

A Latin square is a $ 3 \times 3 $ grid made up of the letters $ \texttt{A} $ , $ \texttt{B} $ , and $ \texttt{C} $ such that: - in each row, the letters $ \texttt{A} $ , $ \texttt{B} $ , and $ \texttt{C} $ each appear once, and - in each column, the letters $ \texttt{A} $ , $ \texttt{B} $ , and $ \texttt{C} $ each appear once. For example, one possible Latin square is shown below. $ $$$\begin{bmatrix} \texttt{A} & \texttt{B} & \texttt{C} \\ \texttt{C} & \texttt{A} & \texttt{B} \\ \texttt{B} & \texttt{C} & \texttt{A} \\ \end{bmatrix} $ $

You are given a Latin square, but one of the letters was replaced with a question mark $ \texttt{?}$$$. Find the letter that was replaced.

The first line of the input contains a single integer $ t $ ( $ 1 \leq t \leq 108 $ ) — the number of testcases. Each test case contains three lines, each consisting of three characters, representing the Latin square. Each character is one of $ \texttt{A} $ , $ \texttt{B} $ , $ \texttt{C} $ , or $ \texttt{?} $ . Each test case is a Latin square with exactly one of the letters replaced with a question mark $ \texttt{?} $ .

For each test case, output the letter that was replaced.

The correct Latin squares for the three test cases are shown below: $ $$$\begin{bmatrix} \texttt{A} & \texttt{B} & \texttt{C} \\ \texttt{C} & \color{red}{\texttt{A}} & \texttt{B} \\ \texttt{B} & \texttt{C} & \texttt{A} \\ \end{bmatrix} \quad \begin{bmatrix} \texttt{B} & \texttt{C} & \texttt{A} \\ \texttt{C} & \texttt{A} & \color{red}{\texttt{B}} \\ \texttt{A} & \texttt{B} & \texttt{C} \\ \end{bmatrix} \quad \begin{bmatrix} \color{red}{\texttt{C}} & \texttt{A} & \texttt{B} \\ \texttt{B} & \texttt{C} & \texttt{A} \\ \texttt{A} & \texttt{B} & \texttt{C} \\ \end{bmatrix} $ $$$