#include <bits/stdc++.h>
using namespace std;
#define int long long
const int MAX = 1e3 + 10;
const double INF = 1e18;
vector<pair<int, double>> adj[MAX];
vector<int> vis(MAX, 0);
vector<double> dis(MAX, INF);
void dij(int k) {
priority_queue<pair<int, int>, vector<pair<int, int>>, greater<pair<int, int>>> q;
q.push({0, k});
dis[k] = 0;
while(q.size()) {
auto [x, u] = q.top();
q.pop();
if(vis[u]) continue;
vis[u] = 1;
for(auto [v, len] : adj[u]) {
if(!vis[v] && dis[u] + len < dis[v]) {
dis[v] = dis[u] + len;
q.push({dis[v], v});
}
}
}
}
void solve() {
vector<int> vt;
int n;
cin >> n;
double a[n + 1];
double b[n + 1];
for(int i = 1; i <= n; i++) {
cin >> a[i] >> b[i];
}
if(n == 1) {
cout << 0.0000000 << endl;
return;
}
for(int i = 1; i <= n; i++) {
for(int j = 1; j <= n; j++) {
if(i != j) {
adj[i].push_back({j, sqrt((abs(a[i] - a[j]) / 2) * (abs(a[i] - a[j]) / 2) + (abs(b[i] - b[j]) / 2) * (abs(b[j] - b[i]) / 2))});
adj[j].push_back({i, sqrt((abs(a[i] - a[j]) / 2) * (abs(a[i] - a[j]) / 2) + (abs(b[i] - b[j]) / 2) * (abs(b[j] - b[i]) / 2))});
}
}
}
for(int i = 1; i <= n; i++) {
if(!vis[i]) {
dij(i);
}
}
double ans = 0;
for(int i = 1; i <= n; i++) {
ans = max(ans, dis[i]);
}
cout << setprecision(7) << fixed << ans << endl;
}
signed main(){
int t = 1;
//cin >> t;
while(t--){
solve();
}
}
