4. The problem is best solved by looking at those people who have not lost each body part. Let A be the set of people who have not lost an eye, B be the set of people who have not lost an ear, C be the set of people who have not lost an arm, and D be the set of people who have not lost a leg. The number of people who have lost all four body parts is smallest if the union of the sets A, B, C and D is as large as possible. Determine how large the union of the sets A, B, C and D can be and use this to determine the least number of pensioners who have lost all four body parts.