Author: Anurag Sahay
Draw a single continuous loop along the gridlines in the diagram. The numbers inside the loop indicate how many of that cell's edges are used by the path. The numbers outside the loop indicate how many of that cell's edges are not used by the path. The path cannot cross or touch itself.
Grid control: To draw a fence click at the cell edge or move mouse along the line holding the button. You can also put auxiliary marks by clicking at cells. More details about grid control are at the help page.