#include <bits/stdc++.h>

using namespace std;

class union_find {
  int n;
  int cnt;           // number of connected components
  vector<int> par;
  vector<int> rank;
  vector<int> sz;    // size of each component
public:
  union_find(int n) : n(n), cnt(n), par(n), rank(n), sz(n) {
    for (int i = 0; i < n; i++) {
      par[i] = i;
      sz[i] = 1;
    }
  }
  
  int find(int x) {
    return par[x] == x ? x : par[x] = find(par[x]);
  }
  
  void unite(int x, int y) {
    x = find(x);
    y = find(y);
    if (x == y) return;
    
    --cnt;
    if (rank[x] < rank[y]) {
      par[x] = y;
      sz[y] += sz[x];
    } else {
      par[y] = x;
      sz[x] += sz[y];
      if (rank[x] == rank[y])
        ++rank[x];
    }
    
  }
  
  bool same(int x, int y) {
    return find(x) == find(y);
  }
  
  int compCnt() {
    return cnt;
  }

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

int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);

  int n;
  cin >> n;

  if (!n) {
    cout << 1 << endl;
    return 0;
  }

  vector<double> x(n), y(n);
  for (int i = 0; i < n; i++)
    cin >> x[i] >> y[i];

  union_find tree(n);
  for (int i = 0; i < n; i++) {
    for (int j = 0; j < i; j++) {
      if ((x[i] - x[j]) * (x[i] - x[j]) + (y[i] - y[j]) * (y[i] - y[j]) <= 100)
        tree.unite(i, j);
    }
  }

  double ret = 0.0;
  for (int i = 0; i < n; i++) {
    for (int j = 0; j < i; j++) {
      if (tree.same(i, j)) {
        ret = max(ret, hypot(x[i] - x[j], y[i] - y[j]));
      }
    }
  }

  ret += 2.0;
  cout << fixed << setprecision(12) << ret << endl;
  
  return 0;
}