#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
const int inf=0x7fffffff;
#define mp(a,b) make_pair(a,b)
const int N=16;
int n;
double dp[N][2^N+1];
pair<double,double> g[N];
double dis[N][N];
int main(){
	scanf("%d",&n);
	for(int i=1;i<=n;i++){
		double x,y;
		scanf("%lf%lf",&x,&y);
		g[i]=mp(x,y);
	} 
	g[0]=make_pair(0,0);
	for(int i=0;i<=n;i++){
		for(int j=i+1;j<=n;j++){
			if(i!=j){
				double x1=g[i].first,y1=g[i].second,x2=g[j].first,y2=g[j].second;
				dis[i][j]=dis[j][i]=sqrt((x1-x2)*(x1-x2)+(y1-y2)*(y1-y2));
			}
		}
	}
	memset(dp,-1,sizeof(dp));
	for(int i=1;i<=n;i++){
		dp[i][2^(i-1)]=dis[0][i];
	}
	for(int i=1;i<=n;i++){
		for(int j=0;j<2^n;j++){
			if(j&(1<<(i-1))!=1||dp[i][j]==-1)continue;
			for(int k=1;k<=n;k++){
				if(j&(1<<(k-1))!=0||k==i)continue;
				if(dp[k][j|(1<<(k-1))]==-1)dp[k][j|(1<<(k-1))]=dp[i][j]+dis[i][k];
				else dp[k][j|(1<<(k-1))]=min(dp[k][j|(1<<(k-1))],dp[i][j]+dis[i][k]);
			}
		}
	}
	double ans=inf;
	for(int i=1;i<=n;i++){
		ans=min(ans,dp[i][2^n-1]);
	}
	printf("%.2lf",ans);
	return 0;
}