#include<bits/stdc++.h>
#define ll long long
namespace IO{
	inline char gc(){
	static const int Rlen=1<<18|1;static char buf[Rlen],*p1,*p2;
	return (p1==p2)&&(p2=(p1=buf)+fread(buf,1,Rlen,stdin),p1==p2)?EOF:*p1++;
	}
	template<typename T>T get_integer(){
		char c;bool f=false;while(!isdigit(c=gc()))f=c=='-';T x=c^48;
		while(isdigit(c=gc()))x=((x+(x<<2))<<1)+(c^48);return f?-x:x;
	}
	inline int gi(){return get_integer<int>();}
}
using namespace std;
using namespace IO;
const int N=1000010;
int n;
struct s{
	int x,y;
	bool operator<(s b){
		return x<b.x;
	}
	bool operator==(s b){
		return x==b.x&&y==b.y;
	}
}p[N];
double dist(s a,s b){
	return sqrt(1ll*(a.x-b.x)*(a.x-b.x)+1ll*(a.y-b.y)*(a.y-b.y));
}
double dis(int i,int j){
	return dist(p[i],p[j]);
}
void solve(){
	double ans=1e18,sum;
	sort(p+1,p+n+1);
	for(int i=1;i<=n;i++){
		for(int j=i+2;j<=min(n,i+300);j++){
			if(dis(i,j)>=ans/2){
				continue;
			}
			if(p[j].x-p[i].x>=ans/2){
				break;
			}
			sum=1e18;
			for(int k=i+1;k<=j-1;k++){
				sum=min(sum,dis(i,k)+dis(k,j));
			}
			ans=min(ans,sum+dis(i,j));
		}
	}
	printf("%.6lf\n",ans);
}
int main(){
	int t=gi();
	for(int tt=1;tt<=t;tt++){
		n=gi();
		for(int i=1;i<=n;i++){
			p[i].x=gi();
			p[i].y=gi();
		}
		printf("Case #%d: ",tt);
		solve();
	}
}