Jaehyun has two lists of integers, namely a1, . . . , aN and b1, . . . , bM. Jeffrey wants to know what these numbers are, but Jaehyun won’t tell him the numbers directly. So, Jeffrey asks Jaehyun a series of questions of the form “How big is ai + bj?” Jaehyun won’t even tell him that, though; instead, he answers either “It’s at least c,” or “It’s at most c.” (Right, Jaehyun simply doesn’t want to give his numbers for whatever reason.) After getting Jaehyun’s responses, Jeffrey tries to guess the numbers, but he cannot figure them out no matter how hard he tries. He starts to wonder if Jaehyun has lied while answering some of the questions.
Write a program to help Jeffrey.
입력 2 1 3 1 1 <= 3 2 1 <= 5 1 1 >= 4 출력 Impossible 입력 2 2 4 1 1 <= 3 2 1 <= 4 1 2 >= 5 2 2 >= 7 출력 Possible
출처:standford/2011/