#include<bits/stdc++.h>using namespace std;#define pb push_back#define mp make_pair#define se second#define fs first#define ll long long#define CLR(x) memset(x,0,sizeof x)#define MC(x,y) memcpy(x,y,sizeof(x))  #define SZ(x) ((int)(x).size())#define FOR(it,c) for(__typeof((c).begin()) it=(c).begin();it!=(c).end();it++)#define lson l,m,rt<<1#define rson m+1,r,rt<<1|1 #define INF 1e9typedef pair<int,int> P;const double eps=1e-9;const int maxnnode=11000;const int maxn=100100;const int mod=20071027;pair<double,double> p[55];double dist[55][55];double dp[55][55];int main(){	int n;	while(~scanf("%d",&n))	{		for(int i=1;i<=n;i++) scanf("%lf%lf",&p[i].fs,&p[i].se);		sort(p+1,p+n+1);		for(int i=1;i<=n;i++)		for(int j=1;j<=n;j++) dp[i][j]=INF;		for(int i=1;i<=n;i++)		for(int j=1;j<=n;j++) dist[i][j]=sqrt((p[i].fs-p[j].fs)*(p[i].fs-p[j].fs)+(p[i].se-p[j].se)*((p[i].se-p[j].se)));		dp[2][1]=dist[2][1];		for(int i=3;i<=n;i++)		{			for(int j=1;j<i-1;j++) dp[i][j]=min(dp[i][j],dp[i-1][j]+dist[i][i-1]);			for(int j=1;j<i-1;j++) dp[i][i-1]=min(dp[i][i-1],dp[i-1][j]+dist[i][j]);		}		double MIN=INF;		for(int i=1;i<=n-1;i++) MIN=min(MIN,dp[n][i]+dist[n][i]);		printf("%.2lf\n",MIN);	}}