Rock Hyraxes are small herbivorous mammals that live in small groups in rocky areas of Africa and the Middle East. They have been known to post sentries to warn the foraging group of nearby predators. Below is an overhead map that shows a Rock Hyrax colony where sentries are posted. The black squares are big boulders that block the view along that row or column. The white squares can either be empty or contain a single Rock Hyrax sentry. The numbers indicate how many sentries are in an adjacent white square, either horizontally or vertically (not diagonally). The sentries can look for predators in all four cardinal directions until their eyesight is blocked by a boulder. No sentry can see another sentry and every white square must be in sight of at least one sentry. A sentry does not necessarily need to be next to a boulder.

It may help to shade in the squares that are in view of a sentry. We’ve done the first one for you.

When complete, the answer to the puzzle will be the number of sentries in the lettered rows, entered as a four digit number ABCD.