r3qknr/p2p3p/nPp3pb/3b1pP1/1PPpPP2/B1N4P/4B2R/R2QK1N1 w Q - 4 18
FEN state: r3qknr/p2p3p/nPp3pb/3b1pP1/1PPpPP2/B1N4P/4B2R/R2QK1N1 w Q - 4 18 ; Best move: b4b5
The current state of the chess board is: Black rook at a8, black queen at e8, black king at f8, black knight at g8 and black rook at h8. Black pawn at a7, black pawn at d7 and black pawn at h7. Black knight at a6, white pawn at b6, black pawn at c6, black pawn at g6 and black bishop at h6. Black bishop at d5, black pawn at f5 and white pawn at g5. White pawn at b4, white pawn at c4, black pawn at d4, white pawn at e4 and white pawn at f4. White bishop at a3, white knight at c3 and white pawn at h3. White bishop at e2 and white rook at h2. White rook at a1, white queen at d1, white king at e1 and white knight at g1. White queenside is the only castle move available. Half move number is 4. Full move number is 18. White to move.