public static void main(String[] args) {
    Point[] ar = new Point[8];
    ar[0] = new Point(0, 0);
    ar[1] = new Point(1, 2);
    ar[2] = new Point(2, 4);
    ar[3] = new Point(1, 3);
    ar[4] = new Point(2, 6);
    ar[5] = new Point(1, 7);
    ar[6] = new Point(-1, 2);
    ar[7] = new Point(-2, -4);

    Shell shel = new Shell(ar, ar.length);
    ar = shel.algJarvis(ar);
    shel.print(ar);
  }