Using K-map

Design a minimized Boolean implementation of an "ones count" circuit that works as follows. The circuit has four binary inputs. A, B, C, D: and generates a 3-bit output: XYZ. The output XYZ is 000 if none of the inputs are 1,001 if one input is 1, 010 if two are one. 011 if three inputs are 1 and 100 if all four inputs are 1. Derive a minimal sum-of-products expression for X, Y, end Z using K-map