#include<bits/stdc++.h>
using namespace std;
const int N=1000010;
struct s{
	int x,y;
	bool operator<(s b){
		return x<b.x;
	}
}p[N],x[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 solve(int l,int r){
	int mid=(l+r)>>1,cnt=0,pos=1;
	double px=(p[mid].x+p[mid+1].x)/2.0,delta,ans;
	if(l==r){
		return 1e18;
	}
	ans=delta=min(solve(l,mid),solve(mid+1,r));
	for(int i=l;i<=r;i++){
		if(abs(px-p[i].x)<=delta/2){
			x[++cnt]=p[i];
		}
	}
	sort(x+1,x+cnt+1,[](s a,s b){return a.y<b.y;});
	for(int i=1;i<=cnt;i++){
		while(pos+1<=cnt&&x[pos+1].y-x[i].y<=delta/2){
			pos++;
		}
		for(int j=i+1;j<=pos;j++){
			for(int k=j+1;k<=pos;k++){
				ans=min(ans,dist(x[i],x[j])+dist(x[i],x[k])+dist(x[j],x[k]));
			}
		}
	}
	return ans;
}
int main(){
	int t,n;
	scanf("%d",&t);
	for(int tt=1;tt<=t;tt++){
		scanf("%d",&n);
		for(int i=1;i<=n;i++){
			scanf("%d%d",&p[i].x,&p[i].y);
		}
		sort(p+1,p+n+1);
		printf("Case #%d: %.6lf\n",tt,solve(1,n));
	}
}