A16420. 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. $$$$\begin{bmatrix} \texttt{A} & \texttt{B} & \texttt{C} \\ \texttt{C} & \texttt{A} & \texttt{B} \\ \texttt{B} & \texttt{C} & \texttt{A} \\ \end{bmatrix} $$ <p>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:

$$$$\begin{bmatrix} \texttt{A} & \texttt{B} & \texttt{C} \\ \texttt{C} & \color{red}{\texttt{A}} & \texttt{B} \\ \texttt{B} & \texttt{C} & \texttt{A} \\ \end{bmatrix} \quad \begin{bmatrix} \texttt{B} & \texttt{C} & \texttt{A} \\ \texttt{C} & \texttt{A} & \color{red}{\texttt{B}} \\ \texttt{A} & \texttt{B} & \texttt{C} \\ \end{bmatrix} \quad \begin{bmatrix} \color{red}{\texttt{C}} & \texttt{A} & \texttt{B} \\ \texttt{B} & \texttt{C} & \texttt{A} \\ \texttt{A} & \texttt{B} & \texttt{C} \\ \end{bmatrix} $$$$