A boatman, a wolf, a sheep, and a cabbage are on the bank of a river. They have a small boat that is capable of carrying the boatman and at most one other animal/item with him. However, if left alone...

Extracted text: A boatman, a wolf, a sheep, and a cabbage are on the bank of a river. They have a small boat that is capable of carrying the boatman and at most one other animal/item with him. However, if left alone by the boatman, the wolf can eat the sheep, and the sheep can eat the cabbage. How can all four be moved safely to the opposite bank of the river? Here is a nice visualization of the whole process in the original game. Disclaimer: writers, testers and CodeChef are not related to this link. This leads to a more general problem. If there are other groups of animals/items with the boatman, is it possible to move them all to the opposite bank of the river in such a way that nobody/nothing gets eaten? We will give you the number of animals/items (not including the boatman). Moreover, we will give you all a list of pairs of the form "X Y" where the X-th animalitem will be eaten by the Y-th one if they are both on the opposite bank to the boatman. You are to determine whether it is possible to achieve the task or not. Input: 1 32 12 23 Output: YES Solve using Python