Pentago rules：
1. Black player first, then black and white players take turn to place own piece.
2. Then select any 3x3 small board and rotate it 90 degrees clockwise or counterclockwise.
3. The first one to make five in the horizontal, vertical or diagonal directions (five consecutive pieces) is the winner.
4. If the board is full and there is still no player make five consecutive pieces, it will be tied.
