#include <bits/stdc++.h>
using namespace std;
#define int long long
#define ld long double
int n;
pair<int, int> a[500010];
ld dis(int i, int j) {
	return sqrtl((a[i].first - a[j].first) * (a[i].first - a[j].first) + (a[i].second - a[j].second) * (a[i].second - a[j].second));
}
signed main() {
	ios::sync_with_stdio(false);
	cin.tie(0), cout.tie(0);
	cin >> n;
	for (int i = 0; i < n; i++)
		cin >> a[i].first >> a[i].second;
	int p = 1, q = 1;
	ld res = 0;
	for (int i = 0; i < n; i++) {
		while (dis(i, p) < dis(i, (p + 1) % n))
			p++;
		while (dis(i, q) <= dis(i, (q + 1) % n))
			q++;
		res = max(res, max(dis(i, p), dis(i, q)));
	}
	cout << fixed << setprecision(7) << res << endl;
	return 0;
}