#define EPS 1e-9

struct Point2 { 
  double x, y; 
  Point2 (double _x=0, double _y=0) : x(_x), y(_y) {}
};

#define DET(a,b,c,d) ((a)*(d)-(b)*(c))
#define SGN(x) ((x)<-EPS ? -1 : (x)>EPS ? 1 : 0) 
#define COLLINEAR(a,b,c) (cw(a,b,c)==0)

double squaredDistance (Point2 p0, Point2 p1) 
{
  double dx = p1.x-p0.x;

  double dy = p1.y-p0.y;
  return dx*dx+dy*dy;
}

char orientation (Point2 p0, Point2 p1, Point2 p2)
{
  return SGN(DET(p1.x-p0.x,p2.x-p0.x,p1.y-p0.y,p2.y-p0.y));
}

int cw (Point2 p0, Point2 p1, Point2 p2)
{
  int o = orientation (p0, p1, p2);

  if (o == 0) // collinear
    return (squaredDistance (p0, p1) < squaredDistance (p0, p2));

  else
    return (o == -1);
}

struct cmp_angle {

  Point2 p0;
  cmp_angle (Point2 p) { p0=p; }
  bool operator() (const Point2& a, const Point2& b) {

    return cw (p0, b, a);
  }
};

bool operator< (const Point2& a, const Point2& b) {

  if (fabs (a.x - b.x) < EPS) return (a.y<b.y);

  return (a.x<b.x);
}