r1b1k1n1/2p3qr/4p1p1/pp1p3p/B2PPbP1/PnP5/2R2P1P/1NBQ1K1R w q - 0 20
FEN state: r1b1k1n1/2p3qr/4p1p1/pp1p3p/B2PPbP1/PnP5/2R2P1P/1NBQ1K1R w q - 0 20 ; Best move: a4b5
The current state of the chess board is: Black rook at a8, black bishop at c8, black king at e8 and black knight at g8. Black pawn at c7, black queen at g7 and black rook at h7. Black pawn at e6 and black pawn at g6. Black pawn at a5, black pawn at b5, black pawn at d5 and black pawn at h5. White bishop at a4, white pawn at d4, white pawn at e4, black bishop at f4 and white pawn at g4. White pawn at a3, black knight at b3 and white pawn at c3. White rook at c2, white pawn at f2 and white pawn at h2. White knight at b1, white bishop at c1, white queen at d1, white king at f1 and white rook at h1. Black queenside is the only castle move available. Half move number is 0. Full move number is 20. White to move.