#include <bits/stdc++.h>

#define REP(i, x, n) for(int i = x; i < (int)(n); i++)
#define rep(i, n) REP(i, 0, n)
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
#define F first
#define S second
#define mp make_pair

using namespace std;

typedef long long ll;
typedef unsigned long long ull;
typedef pair<int, int> P;

class UnionFindTree {
private:
  int nodeSize;
  vector<int> parent;
  vector<int> rank;
  vector<int> treeSize;

public:
  UnionFindTree(int ns) {
    nodeSize = ns;
    parent = vector<int>(nodeSize);
    rank = vector<int>(nodeSize, 0);
    treeSize = vector<int>(nodeSize, 1);

    for(int i = 0; i < nodeSize; i++) {
      parent[i] = i;
    }
  }

  ~UnionFindTree() {}

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

  bool unite(int x, int y) {
    x = find(x);
    y = find(y);
    
    if(x == y) {
      return false;
    }
    
    if(rank[x] < rank[y]) {
      parent[x] = y;
      treeSize[y] += treeSize[x];
    }
    else {
      parent[y] = x;
      treeSize[x] += treeSize[y];
      if(rank[x] == rank[y]) {
        rank[x]++;
      }
    }

    return true;
  }

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

  int getSize(int x) {
    return treeSize[find(x)];
  }
};

int main() {
  // ios_base::sync_with_stdio(false);
  int N;
  cin >> N;
  vector<double> X(N), Y(N);
  rep(i, N) cin >> X[i] >> Y[i];

  UnionFindTree uf(N);

  rep(i, N) REP(j, i + 1, N) {
    if(pow(X[i] - X[j], 2) + pow(Y[i] - Y[j], 2) <= 100) {
      uf.unite(i, j);
    }
  }

  double ans = 2;
  rep(i, N) REP(j, i + 1, N) {
    if(uf.same(i, j)) {
      ans = max(ans, sqrt(pow(X[i] - X[j], 2) + pow(Y[i] - Y[j], 2)) + 2);
    }
  }

  if(N == 0) ans = 1;
  
  printf("%.10f\n", ans);
  
  return 0;
}