65 - ZOJ Monthly, May 2008 - 1004
Caicai is interested in taking photos. But sometimes he finds it annoyed that some people stand in front of him when he is taking photos, which disturbs him from taking the photos of the good views. So he begins to change his position and the angle of view of his camera. But he still can't get a good view. He wonders if anything goes wrong and asks you for help. Your task is to determine the maximum angle of view, so that there exists a position, where if he stands, there is at most one people in the view no matter to which direction he takes photos.
The first line of each test case contains an integer N (3 <= N <= 50), indicating the number of people. The next N lines contain 2 integers each, indicating the position of one person. The absolute values of the coordinates do not exceed 10000.
Note: each person takes little space and one person can't be blocked by another. All the people are not in one line, and No two people stand in the same place.
Output the maximum degree of the angle of view that meets the requirement in one line. Value should be printed truncated to integer, that is to say, if the result is 85.786, you should output 85.
4 0 0 10 0 10 10 0 10 3 0 1 1 0 -1 0 3 0 0 2 2 0 -1
90 120 135
Author: GUAN, Yao