class Tools2D{

  static int area2(Point2D A, Point2D B, Point2D C){
    int x =  (A.x - C.x) * (B.y - C.y) - (A.y - C.y) * (B.x - C.x);
    System.out.println("RESULT: "+x);
    return x;
  }
 
  static boolean insideTriangle(Point2D A, Point2D B, Point2D C, Point2D P){
    boolean inside = 
      Tools2D.area2(A, B, P) >= 0 &&
      Tools2D.area2(B, C, P) >= 0 &&
      Tools2D.area2(C, A, P) >=0;
    System.out.println("---------------");
    return inside;
  }

}