#include <cassert>
#include <cmath>
#include <algorithm>
#include <iostream>
#include <iomanip>
#include <limits.h>
#include <map>
#include <queue>
#include <string.h>
#include <vector>

using namespace std;
typedef long long ll;

const int MAX_N = 200000;
vector<int> parent;
vector<int> _rank;
vector<int> _size;

class UnionFind {
public:
  UnionFind(int n) {
    for (int i = 0; i < n; ++i) {
      parent.push_back(i);
      _rank.push_back(0);
      _size.push_back(1);
    }
  }

  int find(int x) {
    if (parent[x] == x) {
      return x;
    } else {
      return parent[x] = find(parent[x]);
    }
  }

  void unite(int x, int y) {
    x = find(x);
    y = find(y);
    if (x == y) return;

    if (_rank[x] < _rank[y]) {
      parent[x] = y;
      _size[y] += _size[x];
    } else {
      parent[y] = x;
      _size[x] += _size[y];
      if (_rank[x] == _rank[y]) ++_rank[x];
    }
  }

  bool same(int x, int y) {
    return find(x) == find(y);
  }

  int size(int x) {
    return _size[find(x)];
  }
};

int main() {
  int N;

  cin >> N;
  UnionFind uf(MAX_N);

  vector<int> X(N);
  vector<int> Y(N);
  for (int i = 0; i < N; ++i) {
    cin >> X[i] >> Y[i];
    X[i] += 1000;
    Y[i] += 1000;
  }

  for (int i = 0; i < N; ++i) {
    for (int j = 0; j < N; ++j) {
      int dy = (Y[i] - Y[j]);
      int dx = (X[i] - X[j]);
      int dist = dy * dy + dx * dx;

      if (dist <= 10 * 10) {
        uf.unite(i, j);
      }
    }
  }

  double ans = 0.0;

  for (int i = 0; i < N; ++i) {
    for (int j = 0; j < N; ++j) {
      if (not uf.same(i, j)) continue;

      int dy = (Y[i] - Y[j]);
      int dx = (X[i] - X[j]);
      double dist = sqrt(dy * dy + dx * dx);
      ans = max(dist, ans);
    }
  }

  if (N == 0) {
    cout << fixed << setprecision(10) << ans + 1 << endl;
  } else {
    cout << fixed << setprecision(10) << ans + 2 << endl;
  }

  return 0;
}