There are 100 merchants who are selling salmon for Durer dollars around the circular shore of the island of Durerland. Since the beginning of times good and bad years have been alternating on the island. (So after a good year, the next year is bad; and after a bad year, the next year is good.) In every good year all merchants set their price as the maximum value between their own selling price from the year before and the selling price of their left-hand neighbour from the year before. In turn, in every bad year they sell it for the minimum between their own price from the year before and their left-hand neighbour’s price from the year before. Paul and Pauline are two merchants on the island. This year Paul is selling salmon for 17 Durer dollars a kilogram. Prove that there will come a year when Pauline will sell salmon for 17 Durer dollars a kilogram. Note: The merchants are immortal, they have been selling salmon on the island for thousands of years and will continue to do so until the end of time.