#include #include #include #include #include #include #include #include #include #include #include using namespace std; struct Point{ int x; int y; Point(){} Point(int x_, int y_):x(x_),y(y_){} int dist2(int x_, int y_) const{ return (x_-x)*(x_-x) + (y_-y)*(y_-y); } int dist2(const Point& p) const{ return dist2(p.x, p.y); } string str() const{ stringstream st; st << " (" << x << "," << y << ")"; return st.str(); } }; int side(const Point& a1, const Point& a2, const Point& p){ return (a2.x - a1.x) * (p.y - a1.y) - (a2.y - a1.y) * (p.x - a1.x); } bool cross(const Point& a1, const Point& a2, const Point& b1, const Point& b2){ //int s1 = side(a1, a2, b1) * side(a1, a2, b2); int s2 = side(b1, b2, a1) * side(b1, b2, a2); /* if(s1 == 0){// && s2 == 0){ // on a line if(max(a1.dist2(b1), a1.dist2(b2)) < b1.dist2(b2)) return true; if(max(a2.dist2(b1), a2.dist2(b2)) < b1.dist2(b2)) return true; return false; } */ if(s2 <= 0){// && s1 <= 0){ return true; } return false; } int main(){ int N; cin >> N; vector > line(N); vector cand(N*2); for(int i = 0; i < N; i++){ cin >> line[i].first.x; cin >> line[i].first.y; cin >> line[i].second.x; cin >> line[i].second.y; cand[i*2] = line[i].first; cand[i*2+1] = line[i].second; } int ans = 0; for(int i = 0; i < cand.size(); i++){ for(int j = 0; j < cand.size(); j++){ if(cand[i].x == cand[j].x && cand[i].y == cand[j].y) continue; int cnt = 0; for(int k = 0; k < N; k++){ if(cross(line[k].first, line[k].second, cand[i], cand[j])) cnt++; } ans = max(ans, cnt); } } cout << ans << endl; return 0; }