42. You are the chief communications officer for the Lower Slobovian army at war with the Upper Slobovians. Your spies will infiltrate the enemy’s command headquarters in an attempt to gain the “upper” hand. You know the Uppers are planning a major assault, and you also know the following: (1) It will be at either sunrise or sunset, (2) it will come by land, air, or sea, and (3) it will occur on March 28, 29, 30, or 31, or on April 1. Your spies must communicate with you in binary. Devise a suitable binary code for transmitting the information. Try to use the fewest number of bits possible.