#include <iostream>
#include <cmath>
#include <vector>
using namespace std;

double dist(const pair<int, int>& x, const pair<int, int>& y){
	double r = sqrt( (y.first - x.first) * (y.first - x.first) + (y.second - x.second) * (y.second - x.second) );
	return r;
}

int main(){
	int n;
	cin >> n;
	vector<pair<int, int>> m(n);
	for(int i = 0; i < n; i++){
		cin >> m[i].first >> m[i].second;
	}
	vector<vector<int>> dp(n, vector<int>(n, 0));
	int k = 0;
	//dp[0][0] = 0;
	int i = 0, j = 0;
	while(dp[n - 1][n - 1] == 0){
		k = max(i, j) + 1;
		dp[i][k] = min(d[i][k], d[i][j] + dist(m[k], m[j]));
		dp[k][j] = min(d[k][j], d[i][j] + dist(m[k], m[i]));
		i++;j++;
	}
	return 0;
}