#include <bits/stdc++.h>
using namespace std;
#define rep(i, a) for (int i = 0; i < (a); i++)
#define rep2(i, a, b) for (int i = (a); i < (b); i++)
#define repr(i, a) for (int i = (a) - 1; i >= 0; i--)
#define repr2(i, a, b) for (int i = (b) - 1; i >= (a); i--)
template<class T1, class T2> bool chmin(T1 &a, T2 b) { return b < a && (a = b, true); }
template<class T1, class T2> bool chmax(T1 &a, T2 b) { return a < b && (a = b, true); }
typedef long long ll;

typedef double D;
typedef complex<D> P;
const D eps = 0;
D dot(P a, P b) { return real(conj(a) * b); }
D cross(P a, P b) { return imag(conj(a) * b); }

vector<P> convexfull(vector<P> &ps) {
	auto comp = [](P a, P b) {
		if (a.real() != b.real()) return a.real() < b.real();
		return a.imag() < b.imag();
	};
	int n = ps.size();
	sort(ps.begin(), ps.end(), comp);
	int k = 0;
	vector<P> qs(n * 2);
	for (int i = 0; i < n; i++) {
		while (k > 1 && cross(qs[k - 1] - qs[k - 2], ps[i] - qs[k - 1]) <= 0) k--;
		qs[k++] = ps[i];
	}
	for (int i = n - 2, t = k; i >= 0; i--) {
		while (k > t && cross(qs[k - 1] - qs[k - 2], ps[i] - qs[k - 1]) <= 0) k--;
		qs[k++] = ps[i];
	}
	qs.resize(k - 1);
	return qs;
}

double farthest(vector<P> &ps) {
	auto qs = convexfull(ps);
	int n = qs.size();
	if (n == 2) return abs(qs[0] - qs[1]);
	auto comp = [](P a, P b) {
		if (a.real() != b.real()) return a.real() < b.real();
		return a.imag() < b.imag();
	};
	int i = 0, j = 0;
	for (int k = 0; k < n; k++) {
		if (!comp(qs[i], qs[k])) i = k;
		if (comp(qs[j], qs[k])) j = k;
	}
	double ret = 0;
	int si = i, sj = j;
	while (i != sj || j != si) {
		ret = max(ret, abs(qs[i] - qs[j]));
		if (cross(qs[(i + 1) % n] - qs[i], qs[(j + 1) % n] - qs[j]) < 0) {
			i = (i + 1) % n;
		} else {
			j = (j + 1) % n;
		}
	}
	return ret;
}

struct UnionFind {
	vector<int> parent, size;
	UnionFind(int n) : parent(n), size(n, 1) { for (int i = 0; i < n; i++) parent[i] = i; }
	int operator[](int x) { return parent[x] == x ? x : (parent[x] = operator[](parent[x])); }
	bool merge(int x, int y) {
		if ((x = operator[](x)) == (y = operator[](y))) return false;
		parent[x] = parent[y] = size[x] > size[y] ? parent[x] : parent[y];
		size[x] = size[y] = size[x] + size[y];
		return true;
	}
};

ll hypot2(ll x, ll y) {
	return x * x + y * y;
}

int main() {
	int n;
	cin >> n;
	UnionFind uf(n);

	if (n == 0) {
		cout << 1 << endl;
		return 0;
	} else if (n == 1) {
		cout << 2 << endl;
		return 0;
	}

	vector<ll> x(n);
	vector<ll> y(n);
	rep(i, n) scanf("%lld %lld", &x[i], &y[i]);
	rep(i, n - 1) {
		if (hypot2(x[i + 1] - x[i], y[i + 1] - y[i]) <= 100) uf.merge(i, i + 1);
	}
	
	vector<vector<P>> ps(n);
	rep(i, n) ps[uf[i]].emplace_back(x[i], y[i]);

	double ans = 0;
	rep(i, n) if (!ps[i].empty()) chmax(ans, farthest(ps[i]));
	ans += 2;
	printf("%.20f\n", ans);

	return 0;
}