This puzzle was invented by Dr. Gyora Benedek under the name Hidato.

An unsolved puzzle consists of a cluster of squares, sometimes but not always rectangular. Some cells contain numbers.

The goal is fill the grid with numbers from 1 to n, where n is the total number of cells in the puzzle.

The solved grid must satisfy the following conditions:

Each number must be adjacent to the next higher (and lower) number.

Hidato; Numbrix