hash vp(const point& v1, const point& v2, const point& c){
hash ret;
ret.a = v1.dist(c);
ret.b = v2.dist(c);
ret.c = v1.dist(v2);
return ret;
}
double distance(point& p) {
line r(a, b);
auto q = r.closest(p);
if(equals(det(a, b, q), 0) && this->contains(q)) return p.dist(q);
return min(p.dist(a), p.dist(b));
}
bool operator<(const point& b) const {
double crs = b * *this;
if (fabs(crs) > eps)
return crs > 0;
return dist() < b.dist();
}
