#include<bits/stdc++.h>
using namespace std;
using Int = long long;
template<typename T1,typename T2> inline void chmin(T1 &a,T2 b){if(a>b) a=b;}
template<typename T1,typename T2> inline void chmax(T1 &a,T2 b){if(a<b) a=b;}


struct UnionFind{
  Int n;
  vector<Int> r,p;
  UnionFind(){}
  UnionFind(Int sz):n(sz),r(sz,1),p(sz,0){iota(p.begin(),p.end(),0);}
  Int find(Int x){
    return (x==p[x]?x:p[x]=find(p[x]));
  }
  bool same(Int x,Int y){
    return find(x)==find(y);
  }
  void unite(Int x,Int y){
    x=find(x);y=find(y);
    if(x==y) return;
    if(r[x]<r[y]) swap(x,y);
    r[x]+=r[y];
    p[y]=x;
  }
};


struct Precision{
  Precision(){
    cout<<fixed<<setprecision(12);
  }
}precision_beet;

//INSERT ABOVE HERE
signed main(){
  Int n;
  cin>>n;
  vector<Int> x(n),y(n);
  for(Int i=0;i<n;i++) cin>>x[i]>>y[i];
  UnionFind uf(n);
  auto l2norm=[&](Int i,Int j){
                return (x[i]-x[j])*(x[i]-x[j])+(y[i]-y[j])*(y[i]-y[j]);};
  for(Int i=0;i<n;i++)
    for(Int j=0;j<n;j++)
      if(l2norm(i,j)<=100) uf.unite(i,j);

  double ans=1;  
  for(Int i=0;i<n;i++)
    for(Int j=0;j<n;j++)
      if(uf.same(i,j)) chmax(ans,sqrt(double(l2norm(i,j)))+2.0);

  cout<<ans<<endl;
  return 0;
}