#include<bits/stdc++.h>
using namespace std;
#define N 20
struct node{
	long double x,y;
};
int n;
long double dis[N][N],f[1<<N][N];
node id[N];
int main(){
	memset(f,127,sizeof(f));
	long double ans=f[0][0];
	cin>>n;
	for(int i=1;i<=n;i++) cin>>id[i].x>>id[i].y;
	for(int i=0;i<=n;i++)
		for(int j=i+1;j<=n;j++){
			dis[i][j]=sqrt((id[i].x-id[j].x)*(id[i].x-id[j].x)+(id[i].y-id[j].y)*(id[i].y-id[j].y));
			dis[j][i]=dis[i][j];
		}
	for(int i=1;i<=n;i++) f[1<<(i-1)][i]=dis[0][i];
	for(int k=1;k<(1<<n);k++)
		for(int i=1;i<=n;i++){
			if((k&(1<<(i-1)))==0) continue;
			for(int j=1;j<=n;j++){
				if(i==j) continue;
				if((k&(1<<(j-1)))==0) continue;
				f[k][i]=min(f[k][i],f[k-(1<<(i-1))][j]+dis[i][j]);
			}
		}
	for(int i=1;i<=n;i++){
		ans=min(ans,f[(1<<n)-1][i]);
	}
	printf("%.2lf",ans);
	return 0;
}

真看不出有啥问题了