#include<cstdio>#include<cstring>#include<algorithm>#include<cmath>using namespace std;struct Point{ double x,y; Point(double x=0,double y=0):x(x),y(y){}};typedef Point Vector;double eps=1e-10;int dcmp(double x){ if(fabs(x)<eps) return 0; return x<0 ? -1 : 1 ;}Point operator +(Point A,Point B){return Point(A.x+B.x,A.y+B.y);}Point operator -(Point A,Point B){return Point(A.x-B.x,A.y-B.y);}Point operator *(Point A,double p){return Point(A.x*p,A.y*p);}Point operator /(Point A,double p){return Point(A.x/p,A.y/p);}bool operator ==(Point A,Point B){return dcmp(A.x-B.x)==0 && dcmp(A.y-B.y)==0;}bool operator <(Point A,Point B){ if(dcmp(A.x-B.x)==0) return A.y<B.y; return A.x<B.x;}double Cross(Vector A,Vector B){return A.x*B.y-A.y*B.x;}double Dot(Vector A,Vector B){return A.x*B.x+A.y*B.y;}bool parallel(Point aa,Point ab,Point ba,Point bb){return dcmp(Cross(aa-ab,ba-bb))==0;}bool jiaodian(Point aa,Point ab,Point ba,Point bb,Point &as){ if(parallel(aa,ab,ba,bb)) return 0; double s1=Cross(aa-ba,bb-ba); double s2=Cross(ab-ba,bb-ba); as=(ab*s1-aa*s2)/(s1-s2); return 1;}bool onsegment(Point p,Point s,Point t){return dcmp(Cross(s-p,t-p))==0 && dcmp(Dot(s-p,t-p))<=0;}Point p[510],temp,p2[100010];int n,t,tot;int main(){ int i,j,k,ret,ret2; while(~scanf("%d",&n) && n>0) { for(i=1;i<=n;i++)scanf("%lf%lf",&p[i].x,&p[i].y); tot=0; for(i=2;i<=n;i++)for(j=i+1;j<=n;j++) if(jiaodian(p[i],p[i-1],p[j],p[j-1],temp) && onsegment(temp,p[i],p[i-1])&& onsegment(temp,p[j],p[j-1])) p2[++tot]=temp; for(i=1;i<=n;i++)p2[++tot]=p[i]; sort(p2+1,p2+1+tot); ret=1; for(i=2;i<=tot;i++)if(!(p2[i]==p2[i-1])) p2[++ret]=p2[i]; tot=ret; ret2=0; for(i=2;i<=n;i++)for(j=1;j<=tot;j++) if(onsegment(p2[j],p[i],p[i-1])) ret2++; printf("Case %d: There are %d pieces.n",++t,2-tot+ret2-n+1); }}
