#include<bits/stdc++.h>
#define inf 1<<29
#define linf 1e16
#define eps (1e-6)
#define mod 1000000007
#define pi acos(-1)
#define f first
#define s second
#define mp make_pair
#define pb push_back
#define all(a) (a).begin(),(a).end()
#define pd(a) printf("%.10f\n",(double)(a))
#define FOR(i,a,b) for(int i=(a);i<(b);i++)
#define RFOR(i,a,b) for(int i=(a)-1;(b)<=i;i--)
#define equals(a,b) (fabs((a)-(b))<eps)
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int,int> pii;
typedef pair<int,double> pid;
typedef pair<double,int> pdi;
typedef vector<int> vi;
typedef vector<pii> vpi;
const int dx[8]={1,0,-1,0,1,1,-1,-1};
const int dy[8]={0,1,0,-1,1,-1,1,-1};

class Point{
public:
  double x,y;
  Point(double x=0,double y=0):x(x),y(y){}

  Point operator+(Point p){ return Point(x+p.x,y+p.y);}
  Point operator-(Point p){ return Point(x-p.x,y-p.y);}
  Point operator*(double k){ return Point(x*k,y*k);}
  Point operator/(double k){ return Point(x/k,y/k);}
  bool operator<(Point p)const{ 
    return (x!=p.x ? x-p.x<-eps : y-p.y<-eps);}
  bool operator==(Point p)const{ 
    return fabs(x-p.x)<eps && fabs(y-p.y)<eps;}

  double abs(){ return sqrt(norm());}
  double norm(){ return (x*x+y*y);}
};
typedef Point Vector;
typedef vector<Point> Polygon;

class Segment{
public:
  Point p1,p2;
  Segment(Point p1=Point(),Point p2=Point()):p1(p1),p2(p2){}
};
typedef Segment Line;

double norm(Vector a){ return (a.x*a.x+a.y*a.y);}
double abs(Vector a){ return sqrt(norm(a));}
double dot(Vector a,Vector b){ return (a.x*b.x+a.y*b.y);}
double cross(Vector a,Vector b){ return (a.x*b.y-a.y*b.x);}

bool isParallel(Vector a,Vector b){
  return equals(cross(a,b),0.0);
}

bool isParallel(Segment s,Segment t){
  return equals(cross(s.p1-s.p2,t.p1-t.p2),0.0);
}

Point getCrossPointLL(Line a,Line b){
  double A=cross(a.p2-a.p1,b.p2-b.p1);
  double B=cross(a.p2-a.p1,a.p2-b.p1);
  if(abs(A)<eps || abs(B)<eps)return b.p1;
  return b.p1+(b.p2-b.p1)*(B/A);
}

int ccw(Point p0,Point p1,Point p2){
  Vector a=p1-p0;
  Vector b=p2-p0;
  if(cross(a,b)>eps)return 1;
  if(cross(a,b)<-eps)return -1;
  if(dot(a,b)<-eps)return 2;
  if(a.norm()<b.norm())return -2;
  return 0;
}

bool intersect(Point p1,Point p2,Point p3,Point p4){
  return (ccw(p1,p2,p3)*ccw(p1,p2,p4)<=0 &&
          ccw(p3,p4,p1)*ccw(p3,p4,p2)<=0);
}

bool intersect(Segment s1,Segment s2){
  return intersect(s1.p1,s1.p2,s2.p1,s2.p2);
}

bool intersectLS(Line l,Segment s){
  if(cross(l.p2-l.p1,s.p1-l.p1)*
     cross(l.p2-l.p1,s.p2-l.p1)<eps)return true;
  return false;
}
 
int contains(Polygon g,Point p){
  int n=g.size();
  bool x=false;
  for(int i=0;i<n;i++){
    Vector a=g[i]-p,b=g[(i+1)%n]-p;
    if(abs(cross(a,b))<eps && dot(a,b)<eps)return 1;
    if(a.y>b.y)swap(a,b);
    if(a.y<eps && eps<b.y && cross(a,b)>eps)x=!x;
  }
  if(x)return 2;
  return 0;
}

Polygon convex_hull(Polygon s){
  Polygon g;
  int n=s.size();
  if(n<3)return s;

  sort(s.begin(),s.end());

  for(int i=0;i<n;i++){
    for(int n=g.size();n>=2&&ccw(g[n-2],g[n-1],s[i])==1;n--){
      g.pop_back();
    }
    g.push_back(s[i]);
  }
  for(int i=n-2;i>=0;i--){
    for(int n=g.size();n>=2&&ccw(g[n-2],g[n-1],s[i])==1;n--){
      g.pop_back();
    }
    g.push_back(s[i]);
  }
  reverse(g.begin(),g.end());
  g.pop_back();
  return g;
}

vector<Line> getTangent(Polygon a,Polygon b){
  vector<Line> res;
  int n=a.size(),m=b.size();

  FOR(i,0,n){
    FOR(j,0,m){
      int bi=(i+n-1)%n,bj=(j+m-1)%m;
      int ni=(i+1)%n,nj=(j+1)%m;
      if(ccw(a[i],b[j],a[ni])!=-1 && ccw(a[i],b[j],a[bi])!=-1 &&
         ccw(a[i],b[j],b[nj])!=-1 && ccw(a[i],b[j],b[bj])!=-1 ){
        res.pb(Line(a[i],b[j]));
      }
      if(ccw(a[i],b[j],a[ni])!=1 && ccw(a[i],b[j],a[bi])!=1 &&
         ccw(a[i],b[j],b[nj])!=1 && ccw(a[i],b[j],b[bj])!=1){
        res.pb(Line(a[i],b[j]));
      }
      if(ccw(a[i],b[j],a[ni])!=1 && ccw(a[i],b[j],a[bi])!=1 &&
         ccw(a[i],b[j],b[nj])!=-1 && ccw(a[i],b[j],b[bj])!=-1 ){
        res.pb(Line(a[i],b[j]));
      }
      if(ccw(a[i],b[j],a[ni])!=-1 && ccw(a[i],b[j],a[bi])!=-1 &&
         ccw(a[i],b[j],b[nj])!=1 && ccw(a[i],b[j],b[bj])!=1){
        res.pb(Line(a[i],b[j]));
      }
    }
  }
  return res;
}

int n;
Polygon p;

bool check(Segment a){
  if(contains(p,a.p1)==0)return false;
  if(contains(p,a.p2)==0)return false;
  vector<pair<double,Point> > vdp;
  vdp.pb(mp(0,a.p1));
  vdp.pb(mp(abs(a.p1-a.p2),a.p2));
  FOR(i,0,n){
    Segment b(p[i],p[(i+1)%n]);
    if(isParallel(a,b))continue;
    if(!intersect(a,b))continue;
    Point c=getCrossPointLL(a,b);
    vdp.pb(mp(abs(a.p1-c),c));
  }
  sort(all(vdp));
  FOR(i,0,vdp.size()-1){
    Point c=vdp[i].s,d=vdp[i+1].s;
    if(c==d)continue;
    Point m=c+(d-c)/2.0;
    if(contains(p,m)==0)return false;
  }
  return true;
}

double get(Polygon s,Line l){
  vector<Point> vp;
  FOR(i,0,s.size()){
    Point a=s[i],b=s[(i+1)%s.size()];
    if(isParallel(l,Segment(a,b)))continue;
    if(!intersectLS(l,Segment(a,b)))continue;
    Point c=getCrossPointLL(l,Segment(a,b));
    if(!(c==b))vp.pb(c);
  }
  double res=0;
  FOR(i,0,vp.size()){
    FOR(j,i+1,vp.size()){
      
     // pd(abs(vp[i]-vp[j]));
      if(check(Segment(vp[i],vp[j])))res=max(res,abs(vp[i]-vp[j]));
    }
  }
  return res;
}

double solve(){
  double res=0.0;
  FOR(i,0,n)res=max(res,abs(p[i]-p[(i+1)%n]));

  FOR(i,0,n-2){
    FOR(j,i+2,n){
      if((j+1)%n==i)continue;
      Polygon R,L,s;
      s.pb(p[i]);
      s.pb(p[(i+1)%n]);
      s.pb(p[j]);
      s.pb(p[(j+1)%n]);
      Segment s1(s[0],s[3]),s2(s[1],s[2]);
      if(intersect(s1,s2))swap(s1.p2,s2.p2);
      bool flag=true;
      for(int k=(i+1)%n;k!=j;k=(k+1)%n){
        Segment seg=Segment(p[k],p[(k+1)%n]);
        if(isParallel(s1,seg))continue;
        if(!intersect(s1,seg))continue;
        Point tmp=getCrossPointLL(s1,seg);
        if(!(tmp==seg.p1) && !(tmp==seg.p2))flag=false;
      }
      for(int k=(j+1)%n;k!=i;k=(k+1)%n){
        Segment seg=Segment(p[k],p[(k+1)%n]);
        if(isParallel(s2,seg))continue;
        if(!intersect(s2,seg))continue;
        Point tmp=getCrossPointLL(s2,seg);
        if(!(tmp==seg.p1) && !(tmp==seg.p2))flag=false;
      }
      //if(!flag)continue;

      s=convex_hull(s); 

      for(int k=(i+1)%n;k!=(j+1)%n;k=(k+1)%n)
        if(contains(s,p[k])!=0)R.pb(p[k]);
      for(int k=(j+1)%n;k!=(i+1)%n;k=(k+1)%n)
        if(contains(s,p[k])!=0)L.pb(p[k]);
      R=convex_hull(R);
      L=convex_hull(L);
      vector<Line> vs = getTangent(R,L);
      FOR(k,0,R.size()){
        res=max(res,get(s,Segment(R[k],R[(k+1)%R.size()])));
      }
      FOR(k,0,L.size()){
        res=max(res,get(s,Segment(L[k],L[(k+1)%L.size()])));
      }
      FOR(k,0,vs.size()){
        res=max(res,get(s,vs[k]));
      }
    }
  }
  return res;
}

int main()
{
  int c=1;
  while(cin>>n && n){
    p.clear();
    FOR(i,0,n){
      int x,y;
      cin>>x>>y;
      p.pb(Point(x,y));
    }
    cout<<"Case "<<c<<": ";
    pd(solve());
    c++;
  }
  return 0;
}

Measured memory_bytes: 3296