#include<bits/stdc++.h>

using namespace std;

#define ll long long

inline double sq(double d){

    return d*d;

}

int n;

struct Point{

    double x,y;

    double dis(Point &p){

        return sqrt(sq(x-p.x)+sq(y-p.y));

    }

}p[];

double ans=1e64;

int used[];

void dfs(int id,double dis,int cnt=){

    if(cnt>=n){

        //ans=min(ans,dis);

        //printf("%.2f\n",dis);

        if(dis<ans){

            ans=dis;

        }

    }

    else{

        for(int i=;i<=n;i++){

            if(used[i]==/*&&dis+p[id].dis(p[i])<ans*/){

                used[i]=;

                dfs(i,dis+p[id].dis(p[i]),cnt+);

                used[i]=;

            }

        }

    }

}

int main(){

    scanf("%d",&n);

    for(int i=;i<=n;i++){

        scanf("%lf%lf",&p[i].x,&p[i].y);

    }

    p[].x=p[].y=;

    used[]=;

    dfs(,,);

    used[]=;

    printf("%.2f\n",ans);

}