Summary: The bug is found when I try to move a Rook chess from (0, 8) to (0, 9). The program prompted that the move of Rook is judged invalid. However, it is a valid movement. Steps to Reproduce: 1. Run the program 2. Input command "new game" 3. Input command "0 0 0 1" 4. Input command "0 9 0 8" 5. Input command "0 1 0 0" 6. Input command "0 8 0 9" Actual Results: The program prompt "The move you want to make is invalid!" Expected Results: This move is judged valid and successfully performed. No error message will be shown.