
#include <bits/stdc++.h>
#define rep(i,n) for (double i = 0; i < n; ++i)
using namespace std;
typedef long long ll;
typedef pair<double,double> P;
const int INF=1001001001;


vector<P> v;
double dist(double x1,double y1,double x2,double y2){
  double r=0;
  double x=abs(x1-x2);
  double y=abs(y1-y2);
  r=sqrt(x*x+y*y);
  return r;
}

double D(double x,double y){
  double r=0;
  rep(i,v.size()){
    r=max(r,dist(x,y,v[i].first,v[i].second));
   //cout<<r<<endl;
  }
  return r;
}

double g(double x){
  double l=0;
  double r=1500;
  rep(i,80){
    double c1=(2*l+r)/3;
    double c2=(l+2*r)/3;
    double d1=D(x,c1);
    double d2=D(x,c2);
  //  cout<<d1<<' '<<d2<<endl;
    if (d1>d2)l=c1;
    else r=c2;
  }
  return D(x,l);
}


int main(){
  double n;
  cin>>n;
  rep(i,n){
    double x1,y1;
    cin>>x1>>y1;
    P p=make_pair(x1,y1);
    v.push_back(p);

  }
//  cout<<D(1,2);
  double l=0;
  double r=1500;

  rep(i,80){
    double c1=(2*l+r)/3;
    double c2=(l+2*r)/3;
    double d1=g(c1);
    double d2=g(c2);
  //  cout<<d1<<' '<<d2<<endl;
    if (d1>d2)l=c1;
    else r=c2;
  }

  cout<<setprecision(10)<<g(l);

}
