r1bqk1n1/3pb1pr/p7/npp1pp1p/P3PP2/4K1P1/1PPP2NP/RNB1QB1R w q - 1 13
FEN state: r1bqk1n1/3pb1pr/p7/npp1pp1p/P3PP2/4K1P1/1PPP2NP/RNB1QB1R w q - 1 13 ; Best move: a4b5
The current state of the chess board is: Black rook at a8, black bishop at c8, black queen at d8, black king at e8 and black knight at g8. Black pawn at d7, black bishop at e7, black pawn at g7 and black rook at h7. Black pawn at a6. Black knight at a5, black pawn at b5, black pawn at c5, black pawn at e5, black pawn at f5 and black pawn at h5. White pawn at a4, white pawn at e4 and white pawn at f4. White king at e3 and white pawn at g3. White pawn at b2, white pawn at c2, white pawn at d2, white knight at g2 and white pawn at h2. White rook at a1, white knight at b1, white bishop at c1, white queen at e1, white bishop at f1 and white rook at h1. Black queenside is the only castle move available. Half move number is 1. Full move number is 13. White to move.