Author: Иван Грищенко
Draw a closed loop through all cells by connecting the centers horizontally and vertically. The loop can't cross or touch itself. The numbers in the boldly marked area indicate the highest amount of cells that the loop goes through consecutively in that area.
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.