gistfile1.cpp

struct point {
	double x, y;
	point() {
		x=0;
		y=0;
	}
	point(double a, double b) {
		x=a;
		y=b;
	}
	point operator + (point a) {
		return point(x+a.x, y+a.y);
	}
    point operator - (point a) {
		return point(x-a.x, y-a.y);
	}
    double operator * (point a) {
		return x*a.y - y*a.x;
	}
    double operator % (point a) {
		return x*a.x + y*a.y;
	}

	double operator == (point a) {
		return comp_double(x, a.x) && comp_double(y, a.y);
	}

	double operator != (point a) {
		return !comp_double(x, a.x) || !comp_double(y, a.y);
	}

	double length() {
		return sqrt(x*x+y*y);
	}

	point norm() {
		return point(x/length(), y/length());
	}

	void scan() {
		scanf("%lf%lf", &x, &y);
	}
    void print() {
		printf("%lf %lf", x, y);
	}
};