class triangle_program1
{
   public static double Area(Triangle T)
    {
	double peri,area,s,a,b,c;
	peri = T.Perimeter();
	s = peri/2;
	a = T.P.distance_from_point(T.Q);
	b = T.P.distance_from_point(T.R);
	c = T.Q.distance_from_point(T.R);
	area = Math.sqrt(s*(s-a)*(s-b)*(s-c));
	return area;
    }

    public static void main(String args[])
    {
	int x1 = Integer.parseInt(args[0]);
	int y1 = Integer.parseInt(args[1]);
	int x2 = Integer.parseInt(args[2]);
	int y2 = Integer.parseInt(args[3]);
	int x3 = Integer.parseInt(args[4]);
	int y3 = Integer.parseInt(args[5]);

	Triangle T = new Triangle(x1,y1,x2,y2,x3,y3);
	double area = Area(T);
	System.out.println("Area of triangle T is "+area);
    }
}