#include<cstdio>

#include<cstring>

#include<cmath>

#include<iostream>

#include<algorithm>

#include<queue>

using namespace std;

const int maxn = ;

const int maxe = ;

const int INF = 0x3f3f3f;

struct Point{

    double x,y;

    Point(double x=, double y=) : x(x),y(y){ }    //构造函数

};

typedef Point Vector;

Vector operator + (Vector A , Vector B){return Vector(A.x+B.x,A.y+B.y);}

Vector operator - (Vector A , Vector B){return Vector(A.x-B.x,A.y-B.y);}

Vector operator * (Vector A , double p){return Vector(A.x*p,A.y*p);}

Vector operator / (Vector A , double p){return Vector(A.x/p,A.y/p);}

bool operator < (const Point& a,const Point& b){

    return a.x < b.x ||( a.x == b.x && a.y < b.y);

}

const double eps = 1e-;

int dcmp(double x){

    if(fabs(x) < eps) return ;

    else              return x <  ? - : ;

}

bool operator == (const Point& a, const Point& b){

    return dcmp(a.x - b.x) ==  && dcmp(a.y - b.y) == ;

}

///向量（x,y）的极角用atan2(y,x);

double Dot(Vector A, Vector B){ return A.x*B.x + A.y*B.y; }

double Length(Vector A)    { return sqrt(Dot(A,A)); }

double Angle(Vector A, Vector B)  { return acos(Dot(A,B) / Length(A) / Length(B)); }

double Cross(Vector A, Vector B)  { return A.x*B.y - A.y * B.x; }

double Area2(Point A,Point B,Point C) { return Cross(B-A,C-A); }

///向量的逆时针旋转，rad 为旋转的角；

Vector Rotate(Vector A, double rad) { return Vector(A.x*cos(rad)-A.y*sin(rad),A.x*sin(rad)+A.y*cos(rad)); }

///特殊的，下面函数计算向量的单位法向量，即左旋90，在长度归一化；

Vector Normal(Vector A){

    double L = Length(A);

    return Vector(-A.y/L, A.x/L);

}

///直线用参数式 P = P'+ t * v；P'为直线上一点，v为方向向量；

///t不受限制，为直线，t>0 为射线， 0=<t<=1为线段；

///推导暂时不会,下面计算直线P+tv和Q+tw的交点。调用前先确保两直线有唯一交点；即判定Cross(v,w) 非0；

Point GetLineIntersecion(Point P, Vector v,Point Q,Vector w){

    Vector u = P - Q;

    double t = Cross(w,u)/Cross(v,w);

    return P + v*t;

}

///求点到直线的距离，利用h*|AB| == AB(向量) * AP(向量)；

double DistanceToLine(Point P,Point A,Point B){

    Vector v1 = B - A, v2 = P - A;

    return fabs(Cross(v1,v2)) / Length(v1);

}

///求点P到线段AB的距离，先看Q点在线段外还是内；利用点积就可以，

double DistanceToSegment(Point P,Point A,Point B){

    if(A == B)  return Length(P-A);

    Vector v1 = B - A,v2 = P - A,v3 = P - B;

    if(dcmp(Dot(v1,v2)) < )       return Length(v2);

    else if(dcmp(Dot(v1,v3) > ))  return Length(v2);

    else    return  fabs(Cross(v1,v2))/Length(v1);

}

///如果要求Q的话：（当然满足Q在线段内）,由公式Dot(v,P-(A+t'*v)) == 0 推出；

Point GetLineProjection(Point P,Point A,Point B){

    Vector v = B - A;

    return A + v * (Dot(v,P-A)/Dot(v,v));

}

///判定线段是否规范相交；

bool SegmentProperIntersection(Point a1,Point a2,Point b1,Point b2){

    double c1 = Cross(a2-a1,b1-a1), c2 = Cross(a2-a1,b2-a1),

           c3 = Cross(b2-b1,a1-b1), c4 = Cross(b2-b1,a2-b1);

    return dcmp(c1) * dcmp(c2) <  && dcmp(c3) * dcmp(c4) < ;

}

///如果允许在端点处相交：c1和c2都是0，表示两线段共线；如果只有其中一个为0，则一条线段的端点在另一条线段上；

///下面的代码判断一个点P是否在一条线段AB上(不包括A,B点)；

bool OnSegment(Point P,Point A,Point B){

    return dcmp(Cross(A-P,B-P)) ==  && dcmp(Dot(P-A,P-B)) < ;

}

///多边形

///求面积

double PolygonArea(Point* p,int n){

    double area = ;

    for(int i=;i<n-;i++){

        area += Cross(p[i]-p[],p[i+]-p[]);

    }

    return area/;

}

int main()

{

    //freopen("E:\\acm\\input.txt","r",stdin);

    //freopen("E:\\acm\\output.txt","w",stdout);

    Point p[maxn],v[maxn*maxn];

    int n,T=;

    while(scanf("%d",&n)== && n){

       for(int i=;i<n;i++) { scanf("%lf %lf",&p[i].x,&p[i].y); v[i] = p[i]; }

        n--;

        int vcnt = n, ecnt = n;

        for(int i=;i<n;i++)

            for(int j=i+;j<n;j++){

               if( SegmentProperIntersection(p[i],p[i+],p[j],p[j+]) ){

                  v[vcnt++] = GetLineIntersecion(p[i],p[i+]-p[i],p[j],p[j+]-p[j]);

               }

        }

        sort(v,v+vcnt);  ///排序等会好去重；

        vcnt = unique(v,v+vcnt) - v;  ///求出不重复的点的个数；

        for(int i=;i<vcnt;i++)

            for(int j=;j<n;j++)

              if( OnSegment(v[i],p[j],p[j+]) )

                  ecnt++;

        printf("Case %d: There are %d pieces.\n",T++,ecnt+-vcnt);

    }

    return ;

}