Author: Sashika
Draw few rectangular loops through the centers of unshaded cell so that every unshaded cell is used. The sides of different rectangles may intersect each other, but not turn at their intersections or otherwise overlap. Only one rectangle can pass through a cell with letter/number and all letters/numbers at one rectangle should be the same. Also all the same letters/numbers should belong to a single rectangle.
Grid control: To draw a line press the mouse button at a start cell and move mouse to another cell holding the button. More details about grid control are at the help page.