code

#include <bits/stdc++.h>
using namespace std;
double dp[1<<16][25];
double w[25][25];
int n;
double ans=0x7f7f7f7f;
struct node
{
	double x,y;
}c[25];
double d(double xa,double xb,double ya,double yb)
{
	double tmp=(xa-xb)*(xa-xb);
	double temp=(ya-yb)*(ya-yb);
	return double(sqrt(tmp+temp));
}
int main()
{
	memset(dp,127,sizeof dp);
	scanf("%d",&n);
	for(int i=2;i<=n+1;i++)
		scanf("%lf%lf",&c[i].x,&c[i].y);
	n++;
	c[1]={0,0};
	for(int i=1;i<=n;i++)
		for(int j=i+1;j<=n;j++)
			w[i][j]=w[j][i]=d(c[i].x,c[j].x,c[i].y,c[j].y);
	for(int i=1;i<=n;i++)
		dp[i][1<<i-1]=w[1][i];
	for(int s=1;s<(1<<n);s++)
		for(int j=1;j<=n;j++)
		{
			if(!(s&(1<<j-1)))
				continue;
			for(int k=1;k<=n;k++)
			{
				if(j==k)
					continue;
				if(!(s&(1<<k-1)))
					continue;
				dp[s][j]=min(dp[s][j],dp[s^(1<<j-1)][k]+w[k][j]);
			}
		}
	for(int i=2;i<=n;i++)
		ans=min(ans,dp[(1<<n)-1][i]);
	printf("%.2lf\n",ans);
	return 0;
}