ICPC NWERC 2014 F - Finding Lines

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Points: 17
Time limit: 4.0s
Memory limit: 256M

Problem type

Annabel and Richard like to invent new games and play against each other. One day Annabel has a new game for Richard. In this game there is a game master and a player. The game master draws n points on a piece of paper. The task for the player is to find a straight line, such that at least p percent of the points lie exactly on that line. Richard and Annabel have very good tools for measurement and drawing. Therefore they can check whether a point lies exactly on a line or not. If the player can find such a line then the player wins. Otherwise the game master wins the game.

There is just one problem. The game master can draw the points in a way such that it is not possible at all to draw a suitable line. They need an independent mechanism to check whether there even exists a line containing at least p percent of the points, i.e., \lceil \frac{n \cdot p}{100e} \rceil points. Now it is up to you to help them and write a program to solve this task.

Input Specification

The input consists of:

  • one line with one integer n (1 \le n \le 10^5), the number of points the game master has drawn;
  • one line with one integer p (20 \le p \le 100), the percentage of points which need to lie on the line;
  • n lines each with two integers x and y (0 \le x, y \le 10^9), the coordinates of a point.

No two points will coincide.

Output Specification

Output one line containing either possible if it is possible to find a suitable line or impossible otherwise.

Sample Input 1

5
55
0 0
10 10
10 0
0 10
3 3

Sample Output 1

possible

Explanation for Sample 1

A line with (at least) 3 of the points exists.

Sample Input 2

5
45
0 0
10 10
10 0
0 10
3 4

Sample Output 2

impossible

Explanation for Sample 2

No line with at least 3 points exists.


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