#pragma GCC optimize("O3")
#include <iostream>
#include <iomanip>
#include <cstdio>
#include <string>
#include <cstring>
#include <deque>
#include <list>
#include <queue>
#include <stack>
#include <vector>
#include <utility>
#include <algorithm>
#include <map>
#include <set>
#include <complex>
#include <cmath>
#include <limits>
#include <cfloat>
#include <climits>
#include <ctime>
#include <cassert>
#include <numeric>
#include <fstream>
#include <functional>
#include <bitset>
using namespace std;

using ll = long long;
using P = pair<int, int>;
using T = tuple<int, int, int>;

template <class T> inline T chmax(T &a, const T b) {return a = (a < b) ? b : a;}
template <class T> inline T chmin(T &a, const T b) {return a = (a > b) ? b : a;}

constexpr int MOD = 1e9 + 7;
constexpr int inf = 1e9;
constexpr long long INF = 1e18;
constexpr double pi = acos(-1);
constexpr double EPS = 1e-10;

int dx[] = {1, 0, -1, 0};
int dy[] = {0, 1, 0, -1};

int n;

double dijkstra(int s, vector<vector<pair<int, double>>> &G){
    vector<double> dist(n, INF);
    priority_queue<pair<double, int>, vector<pair<double, int>>, greater<pair<double, int>>> que;
    dist[s] = 0;
    que.emplace(0, s);

    while(que.size()){
        double ccost; int cv;
        tie(ccost, cv) = que.top(); que.pop();

        if(dist[cv] < ccost) continue;

        for(auto nxt : G[cv]){
            int nv; double ncost;
            tie(nv, ncost) = nxt;
            
            if(dist[cv] + ncost < dist[nv]){
                dist[nv] = dist[cv] + ncost;
                que.emplace(dist[nv], nv);
            }
        }
    }

    return dist[n-1]; 
}

int main(){
    cin.tie(0);
    ios::sync_with_stdio(false);

    cin>>n;
    vector<double> x(n), y(n);
    for(int i=0; i<n; i++) cin>>x[i]>>y[i];

    ll ng = 0, ok = 1e15;
    while(ok - ng > 1){
        ll mid = (ng + ok) / 2;
        mid *= 10;

        vector<vector<pair<int, double>>> G(n);
        for(int i=0; i<n; i++){
            for(int j=0; j<n; j++){
                if(i == j) continue;
                double cdist = sqrt((x[i] - x[j]) * (x[i] - x[j]) + (y[i] - y[j]) * (y[i] - y[j]));
                if(cdist > (double)mid + EPS) continue;
                G[i].emplace_back(j, cdist);
            }
        }

        double ans = dijkstra(0, G);

        if(ans == INF) ng = mid / 10;
        else ok = mid / 10;
    }

    cout << ok * 10 << endl;

    return 0;
}