rn2k1n1/1qp1p2r/1pN4b/pb3ppp/P4P1P/1PNp1K1R/2PPP1P1/R1BQ1B2 w q - 0 18
FEN state: rn2k1n1/1qp1p2r/1pN4b/pb3ppp/P4P1P/1PNp1K1R/2PPP1P1/R1BQ1B2 w q - 0 18 ; Best move: a4b5
The current state of the chess board is: Black rook at a8, black knight at b8, black king at e8 and black knight at g8. Black queen at b7, black pawn at c7, black pawn at e7 and black rook at h7. Black pawn at b6, white knight at c6 and black bishop at h6. Black pawn at a5, black bishop at b5, black pawn at f5, black pawn at g5 and black pawn at h5. White pawn at a4, white pawn at f4 and white pawn at h4. White pawn at b3, white knight at c3, black pawn at d3, white king at f3 and white rook at h3. White pawn at c2, white pawn at d2, white pawn at e2 and white pawn at g2. White rook at a1, white bishop at c1, white queen at d1 and white bishop at f1. Black queenside is the only castle move available. Half move number is 0. Full move number is 18. White to move.