r1bqkb1r/4pp2/1pp2np1/p1P4p/1P2nN2/P3P3/R2P1PPP/1NB1KBR1 b k - 0 13
FEN state: r1bqkb1r/4pp2/1pp2np1/p1P4p/1P2nN2/P3P3/R2P1PPP/1NB1KBR1 b k - 0 13 ; Best move: a5b4
The current state of the chess board is: Black rook at a8, black bishop at c8, black queen at d8, black king at e8, black bishop at f8 and black rook at h8. Black pawn at e7 and black pawn at f7. Black pawn at b6, black pawn at c6, black knight at f6 and black pawn at g6. Black pawn at a5, white pawn at c5 and black pawn at h5. White pawn at b4, black knight at e4 and white knight at f4. White pawn at a3 and white pawn at e3. White rook at a2, white pawn at d2, white pawn at f2, white pawn at g2 and white pawn at h2. White knight at b1, white bishop at c1, white king at e1, white bishop at f1 and white rook at g1. Black kingside is the only castle move available. Half move number is 0. Full move number is 13. Black to move.