r3k2r/pbq3p1/n1pbpp2/1p3n1p/P2P2NP/2B3P1/1PP1BP1R/RN1Q1K2 w - - 4 18
FEN state: r3k2r/pbq3p1/n1pbpp2/1p3n1p/P2P2NP/2B3P1/1PP1BP1R/RN1Q1K2 w - - 4 18 ; Best move: a4b5
The current state of the chess board is: Black rook at a8, black king at e8 and black rook at h8. Black pawn at a7, black bishop at b7, black queen at c7 and black pawn at g7. Black knight at a6, black pawn at c6, black bishop at d6, black pawn at e6 and black pawn at f6. Black pawn at b5, black knight at f5 and black pawn at h5. White pawn at a4, white pawn at d4, white knight at g4 and white pawn at h4. White bishop at c3 and white pawn at g3. White pawn at b2, white pawn at c2, white bishop at e2, white pawn at f2 and white rook at h2. White rook at a1, white knight at b1, white queen at d1 and white king at f1. Both players have exhausted their castles. Half move number is 4. Full move number is 18. White to move.