#include<bits/stdc++.h>
#define int long long
//ÀýÌ⣺³ÔÄÌÀÒ 
const int INF=0x3f3f3f3f;
using namespace std;
const int N=20;
double dp[1<<N][N]; 
double posx[N],posy[N];
double dis(int a,int b){
	return sqrt(pow(posx[a]-posx[b],2)+pow(posy[a]-posy[b],2));
}
signed main(){
	int n;
	cin>>n; 
	for(int i=1;i<=n;i++)
		cin>>posx[i]>>posy[i];
		
	for (int S = 0; S < (1 << n); S++)
        for (int j = 0; j <= n; j++)
            dp[S][j] = INF;
    
    posx[0] = posy[0] = 0; 
	dp[0][0] = 0;
	
	for(int i=1;i<=n;i++){
		dp[1<<i-1][i]=dis(0,i); 
	} 
	for(int S=1;S<=(1<<n)-1;S++){
		for(int j=1;j<=n;j++){
			if(!(S & (1 << (j - 1)))) continue;
			int Sp = S^((1<<j-1));
			for(int k=0;k<=n;k++){
				if(k == 0 || (Sp & (1 << (k - 1)))){
					dp[S][j] = min(dp[S][j],dp[Sp][k]+dis(k,j));
				}
			}
		}
	}
	double ans=INF;
	for(int k=1;k<=n;k++){
			ans=min(ans,dp[(1<<n)-1][k]);
	}
	printf("%.2f",ans);
	return 0;
}