#include <iostream>
#include <string.h>
#include <math.h>
#include <stdio.h>
using namespace std;
static int n = 0;

double dist(double x1, double y1, double x2, double y2){
	return sqrt(pow(x1-x2, 2.0)+pow(y1-y2,2.0));
}

double minDist(double * points, int startPoint, int * usedPath, int usedSize,int n){
    double md = 100000, temp;
    int newUsedPath[n];
    //printf("startPoint=%d, usedSize=%d , n=%d", startPoint, usedSize, n);
    for(int i=0;i<n;i++){
//    	cout<<"check usedPath["<<i<<"]="<<usedPath[i]<<endl; 
    	if(usedPath[i]){
    		if(usedSize == n-1){
//    			cout<<"return";
        		return dist(points[startPoint*2], points[startPoint*2+1], points[i*2], points[i*2+1]);
			}else{
	        	memcpy(newUsedPath, usedPath, n);
    	    	newUsedPath[i] = 0;
        		temp = minDist(points, i, newUsedPath, usedSize+1,n)+dist(points[startPoint*2], points[startPoint*2+1], points[i*2], points[i*2+1]);
        		newUsedPath[i] = 1;
			}        	
        	if(temp<md){
//   				cout<<"change md from "<<md<<" to "<<temp<<" when startPoint="<<startPoint<<" endPoint="<<i<<endl;
        		md = temp;	
			}     		
//			cout<<"from "<<i<<" to left "<<usedSize-1<<" dist "<<md<<endl;
		}
	}
	return md;
}

int main(){
    //1. input
	cin>>n;
	n++;	
	double points[n][2]; 
	points[0][0] = 0; 
	points[0][1] = 0; 
	int usedPath[n];
	for(int i=1;i<n;i++){
		cin>>points[i][0]>>points[i][1];
    	usedPath[i] = 1;
	}
	//memset(usedPath,1,sizeof(usedPath));
	
	//2. calc
	usedPath[0] = 0;
	double md = minDist(&points[0][0], 0, &usedPath[0], 1,n);
	printf("%.2f",md);
}