#include<bits/stdc++.h>

template<typename T> class Vertex;
template<typename T> class HalfEdge;
template<typename T> class Face;
template<typename T> using HalfEdgePtr = HalfEdge<T>*;


template<typename T>
class Point {
public:
    T x, y;
};

typedef Point<double> PointD;


template<typename T>
class HalfEdge {
public:
    Vertex<T> *origin;
    Face<T> *face;
    HalfEdgePtr<T> nextHE, prevHE, twinHE;
};


template<typename T>
class Vertex {
public:
    Point<T> point;
    HalfEdgePtr<T> halfEdge;
};


template<typename T>
class Face {
public:
    HalfEdgePtr<T> boundary;
    std::vector<HalfEdgePtr<T>> holes;
};


int main() {



    return 0;
}