#include <stdio.h>#include <stdlib.h>#include <string.h>#include <ctype.h>#include <math.h>#include <time.h>#include <iostream>#include <algorithm>#include <cstdio>#include <cstdlib>#include <cmath>#include <cstring>#include <cctype>#include <stack>#include <string>#include <list>#include <queue>#include <map>#include <vector>#include <deque>#include <set>using namespace std;#define INF 0x7F7F7F7F#define eps 1e-8#define PI acos( -1. )#define PI2 asin ( 1. );typedef long long LL;#define MP make_pairtypedef vector<int> VI;typedef vector<int> VS;typedef pair<int , int> PII;#define pb push_back#define mp make_pair#define FOR(a,b,i) for ( i = a ; i < b ; i++ )#define FORE(a,b,i) for ( i = a ; i <= b ; i++ )#define REP(i,n) FOR(0,n,i)#define CL(a,b) memset ( a , b , sizeof ( a ) )#define sqr(a,b) sqrt ( (double)(a)*(a) + (b)*(b) )template < typename T > double DIS ( T va , T vb ) { return sqr ( va.x - vb.x , va.y - vb.y ); }template < class T> inline T INT_LEN( T v ) { int len = 1 ; while ( v /= 10 ) ++len; return len; }template < typename T > inline T square ( T va , T vb ) { return va * va + vb * vb ; }#define cy 55struct P{double x , y ;}ar[cy] , tmp[cy] , goal[cy];int N;void input ( int n ){for ( int i = 0 ; i < n ; i++ ){scanf ( "%lf%lf" , &ar[i].x , &ar[i].y );}ar[n] = ar[0];for ( int i = 0 ; i <= n ; i++ ){tmp[i] = ar[i];}}void splay_len ( P &va , P &vb , double &mx ){double dis = DIS ( va , vb );double p = mx / dis;double L1 = ( vb.x - va.x ) * p;double L2 = ( vb.y - va.y ) * p;va.x -= L1 , va.y -= L2;vb.x += L1 , vb.y += L2;}double det ( P &va , P &vb , P &vc ){return ( vb.x - va.x ) * ( vc.y - va.y ) - ( vc.x - va.x ) * ( vb.y - va.y );}P insec ( P st1 , P ed1 , P st2 , P ed2 ){double eds = fabs ( det ( st1 , ed1 , ed2 ) );double sts = fabs ( det ( st1 , ed1 , st2 ) );P dd;dd.x = ( eds * st2.x + sts * ed2.x ) / ( eds + sts );dd.y = ( eds * st2.y + sts * ed2.y ) / ( eds + sts );return dd;}void left_plane ( P *arr , P *goal , int &la , int &lb , P va , P vb ){double mx = 20000;lb = 0;splay_len ( va , vb , mx );arr[la] = arr[0];double n1 , n2;for ( int i = 0 ; i < la ; i++ ){n1 = det ( va , vb , arr[i] );n2 = det ( va , vb , arr[i + 1] );if ( n1 >= 0 ) goal[lb++] = arr[i];if ( n1 * n2 < 0 ) goal[lb++] = insec ( va , vb , arr[i] , arr[i + 1] );}}void solve ( int n ){int len = n , k = 0;for ( int i = 0 ; i < n ; i++ ){left_plane ( tmp , goal , len , k , ar[i] , ar[-~i] );for ( int j = 0 ; j < k ; j++ ) tmp[j] = goal[j];len = k;}if ( len >= 3 ) puts ( "1" );else puts ( "0" );}int main (void){while ( ~scanf ( "%d" , &N ) && N ){input ( N );solve ( N );}return 0;}
