John was 10 years old and he was a very lazy boy. Of course he had to go to school, but he always tried to work as little as possible. His parents were both doctors and hoped he would become a doctor too in the future. One day, John told his mother he wanted to become a garbage collector. She was very surprised by the choice, since it wasn't a very pleasure job. So, she asked him the reason of that ambition. The boy said he wanted to do that job because garbage collectors work once a week only. His mother asked him for further explanation, as she knew garbage collectors work every day. John told her he used to see them in front of his house only on Wednesday and so they must work once a week only.