Logic Masters Deutschland e.V.

Draw a directed loop through the grid that runs horizontally and vertically, starts and ends in the black circle, and passes through each cell except those with numbers exactly once.

Along the loop, a traveler passes through several grey cells. To be allowed to do so, a pass A 38 is required and will be obtained in cells horizontally, vertically and diagonally neighbouring to cells with numbers. The clue numbers refer to the order in which all neighbouring cells are visited. If N is one of these numbers, and the traveler visits one of these adjacent cells for the N-th time, the traveler receives exactly one pass. If such a cell is also adjacent to other clue cells, it is generally identified by all of them; however, the traveler still receives exactly one pass.

If a grey cell is adjacent to a numbered cell, it is counted in the order in which it is visited, but it can never be the N-th adjacent cell. This means that no pass can be obtained on grey cells.

When traveling through a grey cell, the traveler must have exactly one pass which is then revoked; in other words, the traveler must alternately obtain and use the passes. In the cell with the black circle, the traveler does not have a pass.