r1b2b2/pq2k3/n1p2p1r/Pp1pp2p/1N4pP/1PP1PPP1/1B1P3R/R2QKBN1 w Q - 4 20
FEN state: r1b2b2/pq2k3/n1p2p1r/Pp1pp2p/1N4pP/1PP1PPP1/1B1P3R/R2QKBN1 w Q - 4 20 ; Best move: b4a6
The current state of the chess board is: Black rook at a8, black bishop at c8 and black bishop at f8. Black pawn at a7, black queen at b7 and black king at e7. Black knight at a6, black pawn at c6, black pawn at f6 and black rook at h6. White pawn at a5, black pawn at b5, black pawn at d5, black pawn at e5 and black pawn at h5. White knight at b4, black pawn at g4 and white pawn at h4. White pawn at b3, white pawn at c3, white pawn at e3, white pawn at f3 and white pawn at g3. White bishop at b2, white pawn at d2 and white rook at h2. White rook at a1, white queen at d1, white king at e1, white bishop at f1 and white knight at g1. White queenside is the only castle move available. Half move number is 4. Full move number is 20. White to move.