Reading this maze
Last blank corner starts at row 3, column 1. Of the 30 grid positions, 21 are paintable and 9 are walls. The start is already painted; the other 20 tiles remain to be reached.
Start right from row 3, column 1. The wall stops you at row 3, column 3; keep the side corridors available for a return visit. The first slide covers 3 of 21 target tiles; 18 remain.
The verified opening crosses 2 tiles before stopping. A breadth-first search proves a 17-slide finish from this exact starting board; that is a reference target, not a move limit. You may revisit any painted tile.
