#include <bits/stdc++.h>
using namespace std;

template <typename T, typename U> bool cmin(T &a, U b) { return a > b && (a = b, true); }
template <typename T, typename U> bool cmax(T &a, U b) { return a < b && (a = b, true); }

class UnionFind {
private:
  int N;
  vector<int> PS;

public:
  UnionFind() : N(0) {}
  UnionFind(int n) : N(n), PS(n, -1) {}
  bool unite(int a, int b) {
    int x = root(a), y = root(b);
    if (x == y) return false;
    if (-PS.at(x) < -PS.at(y)) swap(x, y);
    PS.at(x) += PS.at(y);
    PS.at(y) = x;
    return true;
  }
  bool same(int a, int b) { return root(a) == root(b); }
  int root(int a) {
    if (PS.at(a) < 0) return a;
    return PS.at(a) = root(PS.at(a));
  }
  int size(int a) { return -PS.at(root(a)); }
  vector<vector<int>> groups() {
    vector<int> B(N), S(N);
    for (int i = 0; i < N; i++) {
      B.at(i) = root(i);
      S.at(B.at(i))++;
    }
    vector<vector<int>> ret(N);
    for (int i = 0; i < N; i++) {
      ret.at(i).reserve(S.at(i));
    }
    for (int i = 0; i < N; i++) {
      ret.at(B.at(i)).push_back(i);
    }
    auto f = [&](const vector<int> &v) { return v.empty(); };
    ret.erase(remove_if(ret.begin(), ret.end(), f), ret.end());
    return ret;
  }
};

signed main() {
  cin.tie(nullptr);
  ios_base::sync_with_stdio(false);

  int N;
  cin >> N;

  if (!N) return cout << 1 << "\n", 0;

  vector<pair<int, int>> V(N);
  for (int i = 0; i < N; i++) cin >> V.at(i).first >> V.at(i).second;

  UnionFind UF(N);

  for (int i = 0; i < N; i++) {
    for (int j = 0; j < i; j++) {
      auto [a, b] = V.at(i);
      auto [c, d] = V.at(j);
      if (hypot(a - c, b - d) <= 10) UF.unite(i, j);
    }
  }

  double mx = 0;
  for (int i = 0; i < N; i++) {
    for (int j = 0; j < i; j++) {
      auto [a, b] = V.at(i);
      auto [c, d] = V.at(j);
      if (UF.same(i, j)) cmax(mx, hypot(a - c, b - d));
    }
  }

  if (mx == 0) return cout << 2 << "\n", 0;

  cout << fixed << setprecision(6) << mx + 2 << "\n";
}