#define _CRT_SECURE_NO_WARNINGS
#define _USE_MATH_DEFINES

#include "bits/stdc++.h"
#define REP(i,a,b) for(int i=a;i<b;++i)
#define rep(i,n) REP(i,0,n)
#define ll long long
#define ull unsigned ll
typedef long double ld;
#define ALL(a) begin(a),end(a)
#define ifnot(a) if(not a)
#define dump(x)  cerr << #x << " = " << (x) << endl
using namespace std;

// #define int ll
#ifdef _MSC_VER
const bool test = true;
#else 
const bool test = false;
#endif

int dx[] = { 0,1,0,-1 };
int dy[] = { 1,0,-1,0 };
#define INF (1 << 28)
ull mod = (int)1e9 + 7;
//.....................
#define MAX (int)1e6 + 5

struct UnionFind {
	vector<int> data;
	UnionFind(int size) : data(size, -1) { }
	bool unite(int x, int y) {
		x = root(x); y = root(y);
		if (x != y) {
			if (data[y] < data[x]) swap(x, y);
			data[x] += data[y]; data[y] = x;
		}
		return x != y;
	}
	bool same(int x, int y) {
		return root(x) == root(y);
	}
	int root(int x) {
		return data[x] < 0 ? x : data[x] = root(data[x]);
	}
	int size(int x) {
		return -data[root(x)];
	}
};

int N;
double x[1005], y[1005];

void solve() {
	UnionFind uf((int)1e6);
	double ans = 0;
	rep(i, N) {
		cin >> x[i] >> y[i];
	}
	rep(i, N) rep(j, N) {
		if (hypot(x[i] - x[j], y[i] - y[j]) - 1e-6 < 10) {
			uf.unite(i, j);
		}
		// dump(hypot(x[i] - x[j], y[i] - y[j]));
	}
	rep(i, N) rep(j, N) {
		if (uf.same(i, j)) {
			ans = max(ans, hypot(x[i] - x[j], y[i] - y[j]));
		}
	}
	if (ans == 0) puts("1");
	else {
		ans += 2;
		printf("%.20lf\n", ans);
	}
}

signed main() {
	while (cin >> N) {
		solve();
	}
	return 0;
}