#include<bits/stdc++.h>
using namespace std;
int n;
double x[20],y[20],dp[20][40000];
double l(double x1,double x2,double y1,double y2){
	return sqrt((x1-x2)*(x1-x2)+(y1-y2)*(y1-y2));
}
int main(){
	cin>>n;
	for(int i=1;i<=n;i++) cin>>x[i]>>y[i];
	memset(dp,127,sizeof(dp));
	double ans=dp[0][0];
	for(int i=1;i<=n;i++){
		dp[i][(1<<(i-1))]=l(0,x[i],0,y[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(j==i) continue;
				if(k&(i<<(j-1))==0) continue;
				dp[i][k]=min(dp[i][k],dp[j][k-(1<<(i-1))]+l(x[i],x[j],y[i],y[j]));
			}
		}
	}
	for(int i=1;i<=n;i++){
		ans=min(ans,dp[i][(i<<n-1)]);
	}
	printf("%.2lf",ans);
	return 0;
}