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

typedef long long int ll;
typedef unsigned long long int llu;
typedef pair<int, int> pii;
typedef vector<int> vi;
typedef vector<pair<int, int> > vii;

#define rrep(i, m, n) for(int i=m; i<n;  i++)
#define erep(i, n)    for(int i=1; i<=n; i++)
#define  rep(i, n)    for(int i=0; i<n;  i++)
#define rrev(i, m, n) for(int i=n-1; i>=m; i--)
#define erev(i, n)    for(int i=n; i>=1; i--)
#define  rev(i, n)    for(int i=n-1; i>=0; i--)
#define EACH(v)       (v).begin(), (v).end()
#define CNT(a, n, x)  (upper_bound(a, a+n, x)-lower_bound(a, a+n, x))
#define minup(m, x)   (m=min(m, x))
#define maxup(m, x)   (m=max(m, x))
#define mp            make_pair

#define INF 1000000000
#define MOD 1000000009
#define EPS 1E-9

struct UnionFind
{
  vi data;
  UnionFind(int size) : data(size, -1) {}
  bool unite(int x, int y){
    x = root(x);
    y = root(y);
    if(x != y){
      if(data[y] < data[x]) swap(x, y);
      data[x] += data[y];
      data[y] = x;
    }
    return x != y;
  }
  bool same(int x, int y){ return root(x) == root(y); }
  int root(int x){ return data[x] < 0 ? x : data[x] = root(data[x]); }
  int size(int x){ return -data[root(x)]; }
};

#define MAX_N 1000

int n;
int x[MAX_N];
int y[MAX_N];
int res;

#define dist(i, j) ((x[j]-x[i])*(x[j]-x[i]) + (y[j]-y[i])*(y[j]-y[i]))
bool check(int i, int j) { return dist(i, j) <= 100; }

int main()
{
  cin >> n;
  rep(i, n) cin >> x[i] >> y[i];

  UnionFind uf(n);
  rep(i, n) rep(j, n) if(check(i, j))   uf.unite(i, j);
  rep(i, n) rep(j, n) if(uf.same(i, j)) maxup(res, dist(i, j));

  printf("%.10f\n", !n ? 1 : (double)sqrt(res) + 2.0);

  return 0;
}