Author: Andrey Bogdanov
Divide the grid into a set of dominoes. Each domino should be used exactly once. The orientation of the letters does not matter. Black cells are not part of a domino.
Grid control: To draw a cut click at the cell edge or move mouse along the line holding the button. You can also connect the cells which belong to the same domino with auxiliary line. More details about grid control are at the help page.