The wars between Catania and Dogia have last for hundreds of years, and the war has made the people of the two countries. In order to promote peace of the two people, after consultation, the king of the two countries signed a decree, clearly stipulating all the commercial or boys who came to the two countries, must also have crewers from the two countries, and their number must be equal. In a historical day, such a ship finally started navigation. There are 30 crew members on this merchant ship: 15 Catanians and 15 Dangens, the captain is a strong and cold versatian. Not long after sail, the ship met the storm, which was seriously damaged. The captain said that only a way to save this ship is to throw half of the crew to alleviate the load of the boat. For the sake of fairness, he decided to let the crew's draw a lot to decide who came to the cach: Everyone stands into a row, by the captain reading, the crew of the ninth is thrown down. Everyone agreed to this approach. The strange thing is that the crew who is thrown down due to this approach, all Catanians, no a Genian. How did the captain arrange the crew?
