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

#include <iostream>
#include <float.h>
#include <math.h>
using namespace std;

double shortestCycle(int * x, int * y, int size);
void permute(int * a, int left, int right, double ** d, double * result, int size);
int * swap(int * a, int i, int j, int size);

int main()
{
  int n;
  cin >> n;

  int * x = new int [n];
  int * y = new int [n];
  
  for (int i=0; i<n; i++)
  {
    cin >> x[i];
    cin >> y[i];
  }
  cout << shortestCycle(x, y, n);
}

double shortestCycle(int * x, int * y, int size)
{
  double * result = new double[1];
  result[0]= DBL_MAX;
    	    	
  double ** d = new double *[size];
  for(int i=0; i<size; i++)
  {
    d[i] = new double [size];  
  }
      	
  for(int i=0; i<size; i++)
  {
    for(int j=0; j<size; j++)
    {
    	d[i][j] = sqrt((x[i]-x[j])*(x[i]-x[j])+ (y[i]-y[j])*(y[i]-y[j]));
    }
  }
    	
  int * a = new int[size];
  for(int i=0; i<size; i++)
  {
    a[i] = i;
  }
    	
  permute(a, 1, size-1, d, result, size); 
    	
  return result[0];
} 

void permute(int * a, int left, int right, double ** d, double * result, int size) 
{ 
  if (left == right)
  {           
    double rNew = d[a[size-1]][a[0]];
            
    for(int i=0; i<size -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, size); 
      permute(a, left+1, right, d, result, size); 
      a = swap(a,left,i, size); 
    } 
  } 
} 

int * swap(int * a, int i, int j, int size) 
{ 
  int * b = new int[size];
  for(int k=0; k<size; k++)
  {
    b[k] = a[k];
  }
        
  b[i] = a[j];
  b[j] = a[i];
        
  return b;  
}