#include<stdio.h>
#include<math.h>
#include<algorithm>
#include<memory.h>
#include<vector>
using namespace std;

struct Point {
  double x, y;
  Point() {};
  Point(double _x, double _y) {
    x = _x; y = _y;
  }
};

struct Line {
  Point st, ed;
  double a, b, c;

  Line() {}
  Line(Point s, Point e) {
    st = s; ed = e;
    a = ed.y-st.y; 
    b = st.x - ed.x;
    c = -a*st.x-b*st.y;
  }
};

int isCCW(Point a, Point b, Point c) {
  int temp;
  temp  = a.x*b.y - b.x*a.y;
  temp += b.x*c.y - c.x*b.y;
  temp += c.x*a.y - a.x*c.y;

  if(temp > 1e-9) return 1;
  else if(temp < -1e-9) return -1;
  return 0;
}

bool isOnTheSegment(Point st, Point ed, Point p) {
#define maxf(x, y) x > y-1e-9 ? x : y
#define minf(x, y) x < y+1e-9 ? x : y
  Point tSt(minf(st.x, ed.x), minf(st.y, ed.y)), tEd(maxf(st.x, ed.x), maxf(st.y, ed.y));
  if(p.x > tSt.x - 1e-9 && p.x < tEd.x + 1e-9 && p.y > tSt.y - 1e-9 && p.y < tEd.y + 1e-9) {
    if(fabs((ed.y-st.y)*(p.x-st.x) - (ed.x-st.x)*(p.y-st.y)) < 1e-9)
      return true;
  }
  return false;
}

bool isCross(Point p1, Point p2, Point t1, Point t2, bool checkOnTheSegment) {
  int ppt, ttp;
  ppt = isCCW(p1, p2, t1) * isCCW(p1, p2, t2);
  ttp = isCCW(t1, t2, p1) * isCCW(t1, t2, p2);

  if(ppt < 0 && ttp < 0)
    return true;
  else if(checkOnTheSegment)
    return isOnTheSegment(p1, p2, t1) || isOnTheSegment(p1, p2, t2) || isOnTheSegment(t1, t2, p1) || isOnTheSegment(t1, t2, p2);

  return false;
}

Point getCrossPoint(Line a, Line b, bool &is) {
  Point cp;
  if(fabs(a.b*b.a - a.a*b.b) < 1e-9)
    is = false;
  else {
    cp.x = (a.c*b.b - b.c*a.b) / (a.b*b.a - a.a*b.b);
    cp.y = (a.a*b.c - a.c*b.a) / (a.b*b.a - a.a*b.b);
    is = true;
  }

  return cp;
}

int main() {
  freopen("input.in", "r", stdin);

  int n;
  while(scanf("%d", &n) == 1 && n != 0) {
    vector<Point> ps;
    for(int i = 0;i<n;i++) {
      Point temp;
      scanf("%lf%lf", &temp.x, &temp.y);
      ps.push_back(temp);
    }

    vector<Line> edge;
    Point w[4] = {Point(-101.0, 10003.0), Point(-101.0, -101.0), Point(10003.0, -101.0), Point(10003.0, 10003.0)};
    edge.push_back(Line(w[0], w[1]));
    edge.push_back(Line(w[1], w[2]));
    edge.push_back(Line(w[2], w[3]));
    edge.push_back(Line(w[3], w[0]));

    for(int i = 0;i<n;i++) {
      Line l(ps[i], ps[(i+1)%n]);

      Point cp[2];
      int idx[2], nCp = 0, onSeg[2] = {0, 0};
      for(int j = 0;j<edge.size() && nCp < 2;j++) {
        bool is;
        Point tcp = getCrossPoint(l, edge[j], is);
        if(is && isOnTheSegment(edge[j].st, edge[j].ed, tcp)) {
          idx[nCp] = j;
          cp[nCp] = tcp;
          if((fabs(tcp.x - edge[j].st.x) < 1e-9 && fabs(tcp.y - edge[j].st.y) < 1e-9)) {
            onSeg[nCp] = 1;
            j++;
          }
          else if(fabs(tcp.x - edge[j].ed.x) < 1e-9 && fabs(tcp.y - edge[j].ed.y) < 1e-9) {
            onSeg[nCp] = 2;
            j++;
          }
          nCp++;
        }
      }

      if(nCp != 2)
        continue;

      vector<Line> newEdge;
      int nowCCW1 = isCCW(cp[0], cp[1], Point(-101.0, -103.0)), nowCCW2 = isCCW(l.st, l.ed, Point(-101.0, -103.0));
      if(nowCCW1 != nowCCW2) {
        int from = idx[0]+1, to = idx[1]-1;

        newEdge.push_back(Line(cp[1], cp[0]));
        if(onSeg[0] == 0)
          newEdge.push_back(Line(cp[0], edge[idx[0]].ed));
        else if(onSeg[0] == 1)
          from = idx[0];

        for(int i = from;i<=to;i++)
          newEdge.push_back(edge[i]);

        if(onSeg[1] == 0)
          newEdge.push_back(Line(edge[idx[1]].st, cp[1]));
        else if(onSeg[1] == 2)
          to = idx[1];
      }
      else {
        int from = idx[1]+1, to = idx[0]-1;

        newEdge.push_back(Line(cp[0], cp[1]));
        if(onSeg[1] == 0)
          newEdge.push_back(Line(cp[1], edge[idx[1]].ed));
        else if(onSeg[1] == 1)
          to = idx[1];

        for(int i = from;i<edge.size();i++)
          newEdge.push_back(edge[i]);
        for(int i = 0;i<=to;i++)
          newEdge.push_back(edge[i]);

        if(onSeg[0] == 0)
          newEdge.push_back(Line(edge[idx[0]].st, cp[0]));
        else if(onSeg[0] == 2)
          from = idx[0];
      }

      edge = newEdge;
    }

    vector<Line> polygon;
    for(int i = 0;i<n;i++)
      polygon.push_back(Line(ps[i], ps[(i+1)%n]));

    bool isStar = true;
    for(int i = 0;i<edge.size();i++) {
      for(int j = 0;j<n;j++) {
        for(int k = 0;k<polygon.size();k++) {
          if(isCross(edge[i].st, ps[j], polygon[k].st, polygon[k].ed, false)) {
            isStar = false;
            j = n; i = edge.size(); break;
          }
        }
      }
    }
    printf("%d\n", isStar);
  }
}