Any good test case?



import java.util.HashMap;
import java.util.Map;
import java.util.Scanner;

public class Poj1118 {

    private static double getXieLv(int x1, int y1, int x2, int y2) {
        if (x1 == x2) {

            return Double.MAX_VALUE;
        }

        if (y1 == y2) {
            return 0;
        }

        return (y2 - y1 + 0.0) / (x2 - x1 + 0.0);
    }

    /**
     * @param args
     */
    public static void main(String[] args) {
        Scanner cin = new Scanner(System.in);

        while (true) {
            int n = cin.nextInt();

            if (n == 0) {
                break;
            }

            int[] x = new int[n + 1];
            int[] y = new int[n + 1];

            for (int i = 1; i <= n; i++) {
                x[i] = cin.nextInt();
                y[i] = cin.nextInt();
            }

            if (n == 2) {
                System.out.println(2);
                continue;
            }

            // sort the points.
            for (int i = 1; i <= n; i++) {
                for (int j = i + 1; j <= n; j++) {
                    if ((x[i] > x[j]) || (x[i] == x[j] && y[i] > y[j]) ) {
                        int temp = x[i];
                        x[i] = x[j];
                        x[j] = temp;

                        temp = y[i];
                        y[i] = y[j];
                        y[j] = temp;
                    }
                }
            }

            int max = -1;

            for (int i = 1; i <= n; i++) {

                // System.out.println();

                Map<Double, Integer> map = new HashMap<Double, Integer>();

                for (int j = i+1; j <= n; j++) {
                        double value = getXieLv(x[i], y[i], x[j], y[j]);

                        // System.out.println("value=="+ value);

                        Integer ret = map.get(value);

                        if (ret != null) {
                            max = Math.max(max, ret + 1);
                            map.put(value, ret + 1);
                        } else {
                            map.put(value, 1);
                        }
                }
            }

            System.out.println(max + 1);
        }
    }

}