import java.util.Comparator;
import java.util.Collections;
import java.util.ArrayList;
public class Fast {
private static void sort(Comparable[] a, Point compPoint, int lo, int hi) {
if (hi <= lo)
return;
int lt = lo;
int gt = hi;
int i = lo;
int count = 0;
Comparator comp = compPoint.SLOPE_ORDER;
Comparable v = a[lo];
ArrayList<Point> line = new ArrayList<Point>();
line.add(compPoint);
while (i <= gt) {
int cmp = comp.compare(a[i], v);
if (cmp < 0)
exch(a, lt++, i++);
else if (cmp > 0)
exch(a, i, gt--);
else {
count++;
line.add((Point) a[i]);
i++;
}
}
if (count >= 3) {
Collections.sort(line, new Comparator<Point>() {
public int compare(Point v, Point w) {
return v.compareTo(w);
}
});
for (int j = 0; j < line.size(); j++) {
if (j == line.size() - 1)
StdOut.println(line.get(j).toString());
else
StdOut.print(line.get(j).toString()
+ " -> ");
}
line.get(0).drawTo(line.get(line.size() - 1));
}
sort(a, compPoint, lo, lt - 1);
sort(a, compPoint, gt + 1, hi);
}
private static void exch(Comparable[] a, int v, int w) {
Comparable tmp = a[v];
a[v] = a[w];
a[w] = tmp;
}
public static void main(String[] args) {
StdDraw.setXscale(0, 32768);
StdDraw.setYscale(0, 32768);
StdDraw.show(0);
String filename = args[0];
In in = new In(filename);
int N = in.readInt();
Point[] points = new Point[N];
for (int i = 0; i < N; i++) {
int x = in.readInt();
int y = in.readInt();
Point p = new Point(x, y);
points[i] = p;
p.draw();
}
StdRandom.shuffle(points);
for (int i = 0; i < N - 3; i++) {
sort(points, points[i], i + 1, N - 1);
}
StdDraw.show(0);
}
}