Put an arrow into each cell on the edge such that every arrow points horizontally, vertically or diagonally at at least one cell in the grid. Numbers determine how many arrows point at the respective cells. Note: All numbers are either too big or too small and have to be increased or decreased by 1.
Solution code: All arrows, clockwise beginning in the top left: I for arrows points up or down, N for arrows pointing down right or up left, Z for arrows pointing down left or up right, - for arrows pointing left or right