typedef struct Point
{
	int x;
	int y;
};

float distanceBetween(Point p1, Point p2)
{
	return sqrtf((p2.x - p1.x) * (p2.x - p1.x) + (p2.y - p1.y)* (p2.y - p1.y));
}
float pole(Point p1, Point p2, Point p3)
{
	return (float)abs((p1.x * (p2.y - p3.y) + p2.x * (p3.y - p1.y) + p3.x * (p1.y - p2.y))) / 2;
}

float obwod(Point p1, Point p2, Point p3)
{
	return distanceBetween(p1,p2) + distanceBetween(p1,p3) + distanceBetween(p3,p2);
}