#include #include #include #include #include #include #include #include #include #define REP(i,k,n) for(int i=k;i P; struct Point { double x, y; Point(double x=0, double y=0) : x(x), y(y) {} Point operator+(const Point &o) const { return Point(x+o.x, y+o.y); } Point operator-(const Point &o) const { return Point(x-o.x, y-o.y); } Point operator*(const double m) const { return Point(x*m, y*m); } Point operator/(const double d) const { return Point(x/d, y/d); } bool operator<(const Point &o) const { return x != o.x ? x < o.x : y < o.y; } bool operator==(const Point &o) const { return fabs(x-o.x) < EPS && fabs(y-o.y) < EPS; } double cross(const Point &o) const { return x * o.y - y * o.x; } double dot(const Point &o) const { return x * o.x + y * o.y; } double atan() const { return atan2(y, x); } double norm() const { return sqrt(dot(*this)); } double distance(const Point &o) const { return (o - (*this)).norm(); } double area(const Point &a,const Point &b) { Point p = a - (*this), p2 = b - (*this); return p.cross(p2); } double area_abs(const Point &a,const Point &b) const { Point p = a - (*this), p2 = b - (*this); return fabs(p.cross(p2)) / 2.0; } //線分abが自身に含まれているのかどうか判断する int between(const Point &a,const Point &b) { if(area(a,b) != 0) return 0; if(a.x != b.x) return ((a.x <= x) && (x <= b.x) || (a.x >= x) && (x >= b.x)); else return ((a.y <= y) && (y <= b.y) || (a.y >= y) && (y >= b.y)); } double distance_seg(const Point& a,const Point& b) { if((b-a).dot(*this-a) < EPS) { return (*this-a).norm(); } if((a-b).dot(*this-b) < EPS) { return (*this-b).norm(); } return abs((b-a).cross(*this-a)) / (b-a).norm(); } bool hitPolygon(const Point& a,const Point& b,const Point& c) { double t = (b-a).cross(*this-b); double t2 = (c-b).cross(*this-c); double t3 = (a-c).cross(*this-a); if((t > 0 && t2 > 0 && t3 > 0) || ( t < 0 && t2 < 0 && t3 < 0)) { return true; } return false; } }; struct Seg { Point a,b; Seg (Point a, Point b) : a(a),b(b) {} bool isOrthogonal(Seg &s) { return equals((b - a).dot(s.b - s.a),0.0); } bool isParallel(Seg &s) { return equals((b-a).cross(s.b - s.a),0.0); } bool isIntersect(Seg &s) { if(s.a.between(a,b) || s.b.between(a,b) || a.between(s.a,s.b) || b.between(s.a,s.b)) { return true; } return ((a-b).cross(s.a-a) * (a-b).cross(s.b-a) < EPS) && ((s.b-s.a).cross(a-s.a)*(s.b-s.a).cross(b-s.a) < EPS); } bool distance(Seg &s) { if((*this).isIntersect(s)) return 0.0; return min(min(a.distance_seg(s.a,s.b),b.distance_seg(s.a,s.b)),min(s.a.distance_seg(a,b),s.b.distance_seg(a,b))); } Point getCrossPoint(Seg &s) { Point p = s.b - s.a; double d = abs(p.cross(a-s.a)); double d2 = abs(p.cross(b-s.a)); double t = d / (d+d2); return a + (b-a)*t; } }; int main() { int n; cin >> n; vector v; vector seg; rep(i,n) { double a,b,c,d; cin >> a >> b >> c >> d; Point p1(a,b); Point p2(c,d); v.push_back(p1); v.push_back(p2); seg.push_back(Seg(p1,p2)); } int ans = 0; rep(i,v.size()) { rep(j,v.size()) { if(i == j) continue; Seg res(v[i],v[j]); int cnt = 0; rep(k,seg.size()) { if(seg[k].isIntersect(res)) { cnt++; } } ans = max(ans,cnt); } } cout << ans << endl; return 0; }