/* -*- coding: utf-8 -*- * * 245.cc: No.245 貫け! - yukicoder */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include using namespace std; /* constant */ const int MAX_N = 100; const int MAX_N2 = MAX_N * 2; /* typedef */ template struct Pt { T x, y; Pt() {} Pt(T _x, T _y) : x(_x), y(_y) {} Pt(const Pt& pt) : x(pt.x), y(pt.y) {} bool operator==(const Pt pt) const { return x == pt.x && y == pt.y; } Pt operator+(const Pt pt) const { return Pt(x + pt.x, y + pt.y); } Pt operator-() const { return Pt(-x, -y); } Pt operator-(const Pt pt) const { return Pt(x - pt.x, y - pt.y); } Pt operator*(T t) const { return Pt(x * t, y * t); } Pt operator/(T t) const { return Pt(x / t, y / t); } T dot(Pt v) const { return x * v.x + y * v.y; } T cross(Pt v) const { return x * v.y - y * v.x; } Pt mid(const Pt pt) { return Pt((x + pt.x) / 2, (y + pt.y) / 2); } T d2() { return x * x + y * y; } double d() { return sqrt(d2()); } Pt rot(double th) { double c = cos(th), s = sin(th); return Pt(c * x - s * y, s * x + c * y); } Pt rot90() { return Pt(-y, x); } bool operator<(const Pt& pt) const { return x < pt.x || (x == pt.x && y < pt.y); } void print(string format) { printf(("(" + format + ", " + format + ")\n").c_str(), x, y); } void print() { print("%.6lf"); } }; typedef Pt pt; struct CL { pt p; double t0, t1; CL() {} CL(const pt& _p, double _t0, double _t1) : p(_p), t0(_t0), t1(_t1) {} }; /* global variables */ pt pts[MAX_N * 2], vs[MAX_N]; /* subroutines */ bool cross_lines(const pt& ap, const pt av, const pt& bp, const pt bv) { double op01 = av.cross(bv); //if (op01 == 0.0) return false; /* need to handle parallel?? */ if (op01 == 0.0) { pt v = bp - ap; if (v.cross(av) != 0.0) return false; pt a1 = ap + av; pt b1 = bp + bv; return ((bp - ap).dot(b1 - ap) <= 0.0 || (bp - a1).dot(b1 - a1) <= 0.0 || (ap - bp).dot(a1 - bp) <= 0.0 || (ap - b1).dot(a1 - b1) <= 0.0); } pt v = bp - ap; double op0 = v.cross(av); double op1 = v.cross(bv); double t0 = op1 / op01; double t1 = op0 / op01; CL cl; cl.p = bv * t1 + bp; cl.t0 = t0; cl.t1 = t1; return (0.0 <= cl.t0 && cl.t0 <= 1.0 && 0.0 <= cl.t1 && cl.t1 <= 1.0); } /* main */ int main() { int n; cin >> n; int n2 = n * 2; for (int i = 0; i < n2; i++) cin >> pts[i].x >> pts[i].y; for (int i = 0; i < n; i++) vs[i] = pts[i * 2 + 1] - pts[i * 2]; int maxc = 0; for (int i = 0; i < n2; i++) for (int j = i + 1; j < n2; j++) { pt v = pts[j] - pts[i]; int c = 0; for (int k = 0; k < n; k++) if (cross_lines(pts[i], v, pts[k * 2], vs[k])) c++; if (maxc < c) maxc = c; } printf("%d\n", maxc); return 0; }