rnbqkb1r/p3p3/1p1p3p/P1p1N3/3P1p2/2P3P1/1P1B1P1P/R1QnKBNR w K - 4 21
FEN state: rnbqkb1r/p3p3/1p1p3p/P1p1N3/3P1p2/2P3P1/1P1B1P1P/R1QnKBNR w K - 4 21 ; Best move: f1b5
The current state of the chess board is: Black rook at a8, black knight at b8, black bishop at c8, black queen at d8, black king at e8, black bishop at f8 and black rook at h8. Black pawn at a7 and black pawn at e7. Black pawn at b6, black pawn at d6 and black pawn at h6. White pawn at a5, black pawn at c5 and white knight at e5. White pawn at d4 and black pawn at f4. White pawn at c3 and white pawn at g3. White pawn at b2, white bishop at d2, white pawn at f2 and white pawn at h2. White rook at a1, white queen at c1, black knight at d1, 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 4. Full move number is 21. White to move.