Put the numbers 1 through 18 in the eighteen small squares below according to the following rules:

1. Choose a square and put the number 1 in it.
2. Move left, right, up, or down (not diagonally) to an empty square and put a 2 in it.
3. Continue moving in this way. Each time you come to an unfilled square, fill in the next higher number.
4. You may only change directions when you stop to number an unfilled square.
5. You may never pass over any unfilled square, but you may pass over a numbered square.
6. You may not retrace any part of your last move. For example, if the move you just completed was to the right, your next move can't be to the left.
7. Complete the puzzle by filling all 18 squares with the numbers 1 through 18.

There are multiple correct answers.