r1qk1b2/pb1p1p1r/n1p1p2P/1pP2n2/PQ6/7N/1P1PPPBP/RNB1K1R1 b Q - 3 20
FEN state: r1qk1b2/pb1p1p1r/n1p1p2P/1pP2n2/PQ6/7N/1P1PPPBP/RNB1K1R1 b Q - 3 20 ; Best move: a6b4
The current state of the chess board is: Black rook at a8, black queen at c8, black king at d8 and black bishop at f8. Black pawn at a7, black bishop at b7, black pawn at d7, black pawn at f7 and black rook at h7. Black knight at a6, black pawn at c6, black pawn at e6 and white pawn at h6. Black pawn at b5, white pawn at c5 and black knight at f5. White pawn at a4 and white queen at b4. White knight at h3. White pawn at b2, white pawn at d2, white pawn at e2, white pawn at f2, white bishop at g2 and white pawn at h2. White rook at a1, white knight at b1, white bishop at c1, white king at e1 and white rook at g1. White queenside is the only castle move available. Half move number is 3. Full move number is 20. Black to move.