Author: Andrey Bogdanov
Shade some cells black to create a snake - a chain of blackened squares which doesn't touch itself even at a point. Begin and end of the snake are already given. Numbers outside show the length of maximum blackened fragment in the corresponding row or column.
Grid control: Click the mouse button at the selected cell to change the color of the cell. Second click will put auxiliary cross sign, which doesn't affect correctness of the solution, but helps visually. You can also drag the content of one cell to another with the mouse. More details about grid control are at the help page.