d.cpp

#include <bits/stdc++.h>
using namespace std;
const int N = 1005;

const double eps = 1e-7 , pi = acos(-1.0);
inline int dcmp(double x) {
    return (x > eps) - (x < -eps);
}

struct Point {
    double x , y;
    Point (double x = 0 , double y = 0) : x(x) , y(y) {}
    void input() {
        scanf("%lf%lf",&x,&y);
    }
    bool operator < (const Point& R) const {
        if (dcmp(x - R.x) == 0)
            return dcmp(y - R.y) < 0;
        return dcmp(x - R.x) < 0;
    }
    bool operator == (const Point& R) const {
        return dcmp(x - R.x) == 0 && dcmp(y - R.y) == 0;
    }
    Point operator + (const Point& R) const {
        return Point(x + R.x , y + R.y);
    }
    Point operator - (const Point& R) const {
        return Point(x - R.x , y - R.y);
    }
    Point operator * (const double& R) const {
        return Point(x * R , y * R);
    }
    Point operator / (const double& R) const {
        return Point(x / R , y / R);
    }
    double operator ^ (const Point& R) const {
        return x * R.y - y * R.x;
    }
    double operator % (const Point& R) const {
        return x * R.x + y * R.y;
    }
    double len() {
        return sqrt(*this % *this);
    }
    double angle() {
        return atan2(y , x);
    }
};

bool OnRay(Point P , Point a1 , Point a2) {
    double len = (P - a1).len();
    if (dcmp(len) == 0) return true;
    a1 = P - a1 , a2 = P - a2;
    return dcmp((a1 ^ a2) / len) == 0 && dcmp(a1 % (a2 - a1)) >= 0;
}
double GetLineIntersection(Point P , Point v , Point Q , Point w) {
    Point u = P - Q;
    return (w ^ u) / (v ^ w);
}
Point GetLineProjection(Point P , Point A , Point v) {
    return A + v * (v % (P - A) / (v % v));
}

int n;
Point p[N] , P , V;
double r[N];

void work() {
    for (int i = 0 ; i < n ; ++ i) {
        scanf("%lf%lf%lf" , &p[i].x , &p[i].y , &r[i]);
        r[i] = -log10(r[i]);
        //cout << r[i] << endl;
    } p[n] = p[0];

    P = Point(0 , 0);
    scanf("%lf%lf" , &V.x,  &V.y);
    V = V / V.len();

    double I = 0;
    int res = 0 , pre = -1;
    while (I <= 4) {
        ++ res;

        bool point = 0;
        for (int i = 0 ; i < n ; ++ i) {
            if (OnRay(p[i] , P , P + V)) {
                point = 1;
                break;
            }
        }
        if (point) break;
        for (int i = 0 ; i < n ; ++ i) {
            if (i == pre) continue;
            Point w = p[i + 1] - p[i];
            if (dcmp(w ^ V) == 0) continue;
            double t0 = GetLineIntersection(P , V , p[i] , w);
            //cout << t0 << endl;
            if (dcmp(t0) <= 0) continue;
            double t1 = GetLineIntersection(p[i] , w , P , V);
            //cout << t1 << endl;
            if (dcmp(t1) <= 0 || dcmp(t1 - 1) >= 0) continue;
            //cout << "$$$" << endl;
            Point nxt = P + V * t0;
            I += r[i];

            Point O = GetLineProjection(P , nxt , Point(-w.y , w.x));

            V = O + O - P - nxt;
            V = V / V.len();
            P = nxt;
            //printf("%d : %f %f : %f %f | %f\n" , i , P.x , P.y , V.x , V.y , I);
            pre = i;
            break;
        }
        //break;
    }
    printf("%d\n" , res);
}

int main() {
    while (~scanf("%d" , &n)) {
        work();
    }
}