### Number Chain

**Number Chain** is a logic puzzle invented by Leonid Mochalov (Russia). A rectangular or square grid contains numbers from 1 to N in cells. The aim is to draw a single continuous line from the upper left corner to the lower right corner. The line includes each number from 1 to N exactly once.

**Cross+A** can solve puzzles from **4 x 4** to **20 x 20**.