#include<complex>
#include<vector>
#include<iostream>
#include<stack>
#include<cmath>
#include<algorithm>
#include<iomanip>
 
enum CCW{FRONT=0x01,RIGHT=0x02,BACK=0x04,LEFT=0x08,OVER=0x10};
enum CIRCLE_RELATION{CIRCLE_SAME=0x01,CIRCLE_CONTAIN=0x02,
		     CIRCLE_NO_CROSS=0x04,CIRCLE_ONE_CROSS=0x08,
		     CIRCLE_ONE_INSIDE_CROSS=0x10,CIRCLE_TWO_CROSS=0x20};
#define sc second
#define fr first
 
#define REP(i,n) for(int i = 0; i < (int)(n); ++i)
#define foreach(i,o) for(__typeof((o).begin()) i = (o).begin(); i != (o).end(); ++i)
 
using namespace std;
 
typedef double elem;
typedef complex<elem> point, vec;
typedef pair<point, point> line, hline, seg, pp;
 
const elem infty = 1e40;
const elem eps = 1.0e-8;
const elem pi = acos(-1.0);
point base(0,0);
 
// oÍ
ostream &operator<<(ostream &os, const pair<point,point> &p){
  os << p.fr << "-" << p.sc;
  return os;
}
 
// lZ
inline elem sq(elem a){ return a*a; }
inline elem cq(elem a){ return a*a*a; }
 
// pxÏ·
elem rad(elem deg){ return (deg/180)*pi; }
elem deg(elem rad){ return (rad*180)/pi; }
 
// ®¬_Ìô¢AÈÇ
bool eq(elem a, elem b){ return abs(a-b) < eps; }
bool eqv(vec a, vec b){ return eq( abs(b-a),0); }

namespace std{
  bool operator<(const point &a, const point &b){
    if(!eq(a.real(),b.real()))return a.real()<b.real();
    if(!eq(a.imag(),b.imag()))return a.imag()<b.imag();
    return false;
  }
} 

// _Iy[^
bool far(point a, point b){ return abs(b-a)>0; }
bool near(point a, point b){ return abs(b-a)<=0; }
elem dot(vec a, vec b){ return (a.real() * b.real() + a.imag() * b.imag() ); }
elem cross(vec a, vec b){ return ( a.real() * b.imag() - a.imag() * b.real() ); }
 
// a©çbÜÅvñèÌpxAàpA]ñ]
elem varg(vec a, vec b){
  elem ret=arg(a)-arg(b);
  if(ret<0)ret+=2*pi;
  if(ret>2*pi)ret-=2*pi;
  if(eq(ret,2*pi))ret=0;
  return ret;
}
elem varg2(vec a, vec b){
  elem ret = varg(a,b);
  if(ret>pi)return 2*pi-ret;
  return ret;
}
elem arg(vec a, vec b){ return acos( dot(a,b) / ( abs(a) * abs(b) ) ); }
point rot(point p, elem theta){ return p * polar((elem)1.0, theta); }
point rotdeg(point p, elem deg){ return p * polar((elem)1.0, rad(deg)); }
point proj(line l, point p){
  elem t=dot(p-l.first,l.first-l.second)/abs(l.first-l.second);
  return l.first + t*(l.first-l.second);
}
point reflect(line l, point p){ return p+2.0*(proj(l,p)-p); }
 
// ñ_Ô£A¼üÆ_ÌÅZ£AüªÆ_ÌÅZ£
elem dist(point a, point b){ return abs(a-b); }
elem dist_l(line l, point x){ return abs(cross(l.sc-l.fr,x-l.fr)) / abs(l.sc-l.fr); }
elem dist_seg(seg s, point x)
{
  if( dot(s.sc-s.fr,x-s.fr)<0 ) return abs(x-s.fr);
  if( dot(s.fr-s.sc,x-s.sc)<0 ) return abs(x-s.sc);
  return dist_l(s,x);
}
 
// PÊxNgA@üxNgAPÊ@üxNg
vec uvec(vec a){ return a / abs(a); }
vec nmr(vec a){ return a * vec(0,-1); }
vec nml(vec a){ return a * vec(0,1); }
vec unmr(vec a){ return uvec( nmr(a) ); }
vec unml(vec a){ return uvec( nml(a) ); }
 
// ¼ðA½s»è
bool orth(point a1, point a2, point b1, point b2){ return eq( dot( a2 - a1, b2 - b1 ), 0 ); }
bool orth(vec v1, vec v2){ return eq( dot(v1, v2), 0 ); }
bool prll(point a1, point a2, point b1, point b2){ return eq( cross( a2 - a1, b2 - b1 ), 0 ); }
bool prll(vec v1, vec v2){ return eq( cross(v1, v2), 0 ); }
 
// CCW oXg¾ªA¸xÉæé
inline int ccw(const point &a, point b, point x){
  b -= a;
  x -= a;
  if( eq(cross(b,x),0.0) && dot(b,x) < 0 ) return BACK;
  if( eq(cross(b,x),0.0) && abs(b) < abs(x) ) return FRONT;
  if( eq(cross(b,x),0.0) ) return OVER;
  if( cross(b,x) > 0 ) return LEFT;
  if( cross(b,x) < 0 ) return RIGHT;
}
 
// üªg£
line expandLine(line l, elem mag){
  line ret = l;
  vec vf(l.first - l.second);
  vec vs(l.second - l.first);
  ret.first = l.second + mag * vf;
  ret.second = l.first + mag * vs;
  return ret;
}
 
// üªÌð·»è
inline bool intersectedSS(const seg &a, const seg &b)
{
  int cwaf=ccw(a.fr,a.sc,b.fr);
  int cwbf=ccw(b.fr,b.sc,a.fr);
  int cwas=ccw(a.fr,a.sc,b.sc);
  int cwbs=ccw(b.fr,b.sc,a.sc);
  if( cwaf==OVER || cwas==OVER || cwbf==OVER || cwbs==OVER ) return true;
  return ( cwaf | cwas ) == (LEFT|RIGHT) && ( cwbf | cwbs ) == (LEFT|RIGHT);
}
 
// ¼üÌð·»è
bool intersectedLL(line a, line b){ return !eq( cross(a.sc-a.fr,b.sc-b.fr), 0.0 ); }
 
// ð_vZ
point intersectionSS(seg a, seg b)
{
  elem d1 = dist_l(b,a.fr);
  elem d2 = dist_l(b,a.sc);
  return a.fr + ( d1 / (d1 + d2 ) ) * (a.sc-a.fr);
}
point intersectionLL(line a, line b)
{
  vec va = a.sc - a.fr;
  vec vb = b.sc - b.fr;
  return a.fr + va * ( cross(vb, b.fr - a.fr) / cross(vb,va) );
}
 
// üªð_êÅ
bool intersectionLL(line a, line b, point &ret){
  return intersectedLL( a, b ) ? ret = intersectionLL( a, b ), true : false;
}
bool intersectionLH(line a, hline b, point &ret){
  point tmp;
  return intersectionLL(a,b,tmp) ? ( ccw(b.fr,b.sc,tmp)&(OVER|FRONT) ? ret=tmp, true : false ) : false;
}
bool intersectionLS(line l, seg s, point &ret){
  point tmp;
  return intersectionLL(l,s,tmp) ? ( ccw(s.fr,s.sc,tmp)&OVER ? ret=tmp, true : false ) : false;
}
bool intersectionHH(hline a, hline b, point &ret){
  point tmp;
  return intersectionLL(a,b,tmp) ? ( ccw(a.fr,a.sc,tmp)&(OVER|FRONT)&&ccw(b.fr,b.sc,tmp)&(OVER|FRONT) ? ret = tmp, true : false ) : false;
}
bool intersectionHS(hline a, seg s, point &ret){
  point tmp;
  return intersectionLS(a,s,tmp) ? ( ccw(a.fr,a.sc,tmp)&(OVER|FRONT) ? ret = tmp, true : false ) : false;
}
bool intersectionSS(seg a, seg b, point &ret){
  return intersectedSS(a,b) ? ret = intersectionSS(a,b), true : false;
}

elem areaOfPolygon(const vector<point> &vp){
  elem ret = 0;
  for(int i = 0; i < (int)vp.size(); ++i){
    ret += cross(vp[i],vp[(i+1)%vp.size()]);
  }
  return abs(ret/2.0);
}

bool cmpXy(const point &a, const point &b){
  if( eq(a.real(),b.real() ) ) return a.imag()<b.imag();
  if( a.real()<b.real() ) return true;
  return false;
}

// Ah[Êï(verified),CHÍ½vñè
void andrewConvexHull(const vector<point> &Q, vector<point> &CH)
{
  vector<point> T = Q;
  int n = T.size(), k = 0;
  if( Q.size() < 3 ){
    CH = Q;
    return ;
  }
  sort( T.begin(), T.end(), cmpXy );
  CH.resize(2*n);
  for(int i = 0; i < n; CH[k++] = T[i++]){
    while( k >= 2 && ccw( CH[k-2], CH[k-1], T[i] ) & ( RIGHT | BACK ) ) --k;
  }
  for(int i = n-2, t = k+1; i >= 0; CH[k++] = T[i--] ){
    while( k >= t && ccw( CH[k-2], CH[k-1], T[i] ) & ( RIGHT | BACK ) ) --k;
  }
  CH.resize(k-1);
}

bool regularConvex(vector<point> &vp){
  vector<point> ret;
  for(int i = 0; i < (int)vp.size(); ++i){
    for(int j = i+1; j < (int)vp.size(); ++j){
      if( near(vp[i],vp[j]) ){
        vp.erase( vp.begin() + j );
      }
    }
  }
  andrewConvexHull( vp, ret );
  vp = ret;
}

// ÊïJbg(ACC AOJ 1050) -> modified and not verified
bool convexCut(const vector<point> &vp,
	       line l,
	       vector<point> &left)
{
  vector<point> tmp;
  for(int i = 0; i < (int)vp.size(); ++i){
    if( ccw(l.fr, l.sc, vp[i] ) == LEFT ){
      tmp.push_back(vp[i]);
    }
  }
  for(int i = 0; i < (int)vp.size(); ++i){
    point is;
    seg s(vp[i],vp[(i+1)%vp.size()]);
    if(intersectionLS( l, s, is )){
      tmp.push_back(is);
    }
  }
  regularConvex(tmp);
  left = tmp;
  return true;
}

int main(){
  while(true){
    int N;
    cin >> N;
    if( N == 0 ) break;
    vector<point> vp;
    vector<point> plane;

    plane.push_back(point(-100,-100));
    plane.push_back(point(10100,-100));
    plane.push_back(point(10100,10100));
    plane.push_back(point(-100,10100));

    for(int i = 0; i < N; ++i){
      point p;
      cin >> p.real() >> p.imag();
      vp.push_back(p);
    }
    
    bool ng = false;
    for(int i = 0; i < (int)vp.size(); ++i){
      vector<point> newPlane;
      line cutting(vp[i],vp[(i+1)%vp.size()]);
      convexCut( plane, cutting, newPlane );
      plane = newPlane;
      if(plane.size()<3||eq(areaOfPolygon(plane),0))ng=true;
    }

    if(ng){
      cout << 0 << endl;
    }else{
      cout << 1 << endl;
    }
  }
  return 0;
}

Measured memory_bytes: 0