#include <cstdio>

#include <cmath>

#define N 25

double calc(double x1,double y1,double x2,double y2)

{

    return sqrt((double)(x1-x2)*(x1-x2)+(double)(y1-y2)*(y1-y2));

}

int n;

bool vis[N];

double f[N][N],x[N],y[N],ans=1e9;

double minn(double a,double b) {return a>b?b:a;}

void dfs(int now,int num,double dist)

{

    if(num==n) {ans=minn(ans,dist);return;}

    if(dist>ans) return;

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

    {

        if(now==i||vis[i]) continue;

        vis[i]=;

        dfs(i,num+,dist+f[now][i]);

        vis[i]=;

    }

}

int main()

{

    scanf("%d",&n);

    for(int i=;i<=n;++i) scanf("%lf%lf",&x[i],&y[i]),f[][i]=calc(,,x[i],y[i]);

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

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

      f[i][j]=f[j][i]=calc(x[i],y[i],x[j],y[j]);

    dfs(,,);

    printf("%.2lf",ans);

    return ;

}