// 2023 IUSB Programming Competition
// Round 2 Problem 3
// Shortest Cycle
// Solution by Liguo Yu

import java.util.Scanner;

public class round2_p3
{	
    public static void main(String[] args)
    {
    	Scanner input = new Scanner(System.in);
    	
    	int n = input.nextInt();
    	
    	int[] x = new int[n];
    	int[] y = new int[n];
    	
    	for(int i=0; i<n; i++)
    	{
        	x[i] = input.nextInt();
        	y[i] = input.nextInt();
    	}
    	
    	System.out.println(shortestCycle(x, y)); 	
    }
    
    public static double shortestCycle(int[] x, int[] y)
    {
    	double[] result = new double[1];
        result[0]= Double.MAX_VALUE;
    	    	
    	int n = x.length;
    	double[][] d = new double[n][n];
    	
    	for(int i=0; i<n; i++)
    	{
    		for(int j=0; j<n; j++)
    		{
    			d[i][j] = Math.sqrt((x[i]-x[j])*(x[i]-x[j])+ (y[i]-y[j])*(y[i]-y[j]));
    		}
    	}
    	
    	int[] a = new int[n];
    	for(int i=0; i<n; i++)
    	{
    		a[i] = i;
    	}
    	
    	permute(a, 1, n-1, d, result); 
    	
    	return result[0];
    } 
  
    public static void permute(int[] a, int left, int right, double[][] d, double[] result) 
    { 
        if (left == right)
        {           
            double rNew = d[a[a.length-1]][a[0]];
            
            for(int i=0; i<a.length -1; i++)
            {
            	rNew = rNew + d[a[i]][a[i+1]];
            }
            
            if(rNew < result[0]) result[0] = rNew;   
        }
        
        else
        { 
            for (int i = left; i <= right; i++) 
            { 
                a = swap(a,left,i); 
                permute(a, left+1, right, d, result); 
                a = swap(a,left,i); 
            } 
        } 

    } 
    
    public static int[] swap(int[] a, int i, int j) 
    { 
        int[] b = new int[a.length];
        for(int k=0; k<a.length; k++)
        {
        	b[k] = a[k];
        }
        
        b[i] = a[j];
        b[j] = a[i];
        
        return b; 
    } 
}