Author: Anurag Sahay
Draw a single non-intersecting loop in the grid that visits each bold region. Within every area, the loop visits all cells of one color and leaves all of the other.
Grid control: To draw a line press the mouse button at a start cell and move mouse to another cell holding the button. You can also put auxiliary marks which don't affect submission by clicking at cells. More details about grid control are at the help page.