rn1qkbn1/1bpp1p2/2r1p3/p6p/1NPPQ1PP/P6B/1P1K1P2/RNB2R2 b q - 5 21
FEN state: rn1qkbn1/1bpp1p2/2r1p3/p6p/1NPPQ1PP/P6B/1P1K1P2/RNB2R2 b q - 5 21 ; Best move: a5b4
The current state of the chess board is: Black rook at a8, black knight at b8, black queen at d8, black king at e8, black bishop at f8 and black knight at g8. Black bishop at b7, black pawn at c7, black pawn at d7 and black pawn at f7. Black rook at c6 and black pawn at e6. Black pawn at a5 and black pawn at h5. White knight at b4, white pawn at c4, white pawn at d4, white queen at e4, white pawn at g4 and white pawn at h4. White pawn at a3 and white bishop at h3. White pawn at b2, white king at d2 and white pawn at f2. White rook at a1, white knight at b1, white bishop at c1 and white rook at f1. Black queenside is the only castle move available. Half move number is 5. Full move number is 21. Black to move.