1rbkr3/ppp1n1Bp/8/b1np1p2/5PP1/P1PPp3/1P1NP2P/1R2KBNR w K - 1 20
FEN state: 1rbkr3/ppp1n1Bp/8/b1np1p2/5PP1/P1PPp3/1P1NP2P/1R2KBNR w K - 1 20 ; Best move: b2b4
The current state of the chess board is: Black rook at b8, black bishop at c8, black king at d8 and black rook at e8. Black pawn at a7, black pawn at b7, black pawn at c7, black knight at e7, white bishop at g7 and black pawn at h7. Black bishop at a5, black knight at c5, black pawn at d5 and black pawn at f5. White pawn at f4 and white pawn at g4. White pawn at a3, white pawn at c3, white pawn at d3 and black pawn at e3. White pawn at b2, white knight at d2, white pawn at e2 and white pawn at h2. White rook at b1, white king at e1, white bishop at f1, white knight at g1 and white rook at h1. White kingside is the only castle move available. Half move number is 1. Full move number is 20. White to move.