#include <iostream>
#include <vector>
#include <algorithm>
#include <cmath>
#include <iomanip>

using namespace std;

int n;
vector<int> x, y;
vector<bool> visited;
vector<int> connectedNodes;

int getNorm(int node1, int node2) {
	return (x[node1] - x[node2]) * (x[node1] - x[node2])
		+ (y[node1] - y[node2]) * (y[node1] - y[node2]);
}

void findConnectedNodes(int node) {
	if (visited[node]) {
		return;
	}
	visited[node] = true;
	connectedNodes.push_back(node);
	for (int i = 0; i < n; ++i) {
		if (node != i) {
			if (getNorm(i, node) <= 10 * 10) {
				findConnectedNodes(i);
			}
		}
	}
}

int main() {
	cin >> n;
	x.resize(n);
	y.resize(n);
	for (int i = 0; i < n; ++i) {
		cin >> x[i] >> y[i];
	}
	visited.resize(n);
	double maxDistance = 0;
	if (n > 0) {
		for (int i = 0; i < n; ++i) {
			connectedNodes.clear();
			if (visited[i]) {
				continue;
			}
			connectedNodes.push_back(i);
			findConnectedNodes(i);
			double distance;
			if (connectedNodes.size() > 1) {
				int maxNorm = 0;
				pair<int, int> maxNormNodes;
				for (size_t k = 0; k < connectedNodes.size(); ++k) {
					for (size_t m = k + 1; m < connectedNodes.size(); ++m) {
						int node1 = connectedNodes[k];
						int node2 = connectedNodes[m];
						int norm = getNorm(node1, node2);
						if (maxNorm < norm) {
							maxNorm = norm;
							maxNormNodes = make_pair(node1, node2);
						}
					}
				}
				distance = sqrt(getNorm(maxNormNodes.first, maxNormNodes.second));
				distance += 2.0;
			} else {
				distance = 2.0;
			}
			maxDistance = max(maxDistance, distance);
		}
	} else {
		maxDistance = 1.0;
	}
	cout << fixed << setprecision(12) << maxDistance << endl;
	return 0;
}