Fill each cell (octagons and squares) with a digit from 1-9. Cells sharing an edge can't have the same digit. Each horizontal row and vertical column contains a non-repeating consecutive set of digits (like 2345678) in any order. A value in an external cell represents the rank of the number formed by reading the digits in the indicated 5-cell diagonal from that direction, where (1) is the lowest such row or column and (20) is the highest. If two ranks are tied, the value in both external cells is the lower of the two ranks being shared.Eg, if the lowest four ranks are '12453', '13524', '13524' and '15432', the values in the relevant external cells would be (1), (2), (2) and (4) respectively.