#include<bits/stdc++.h>

 #define inf 0x3f3f3f3f

 using namespace std;

 typedef long long ll;

 typedef pair<int,int> pll;

 const int maxn=1e5+;

 const int mod =1e9+;

 const double EPS = 1e-;

 struct node

 {

     double x;

     double y;

 };

 node s[maxn];

 int n;

 double Calc(double num)

 {

     double ans=;

     for(int i=;i<=n;i++)

     {

         double q=sqrt((num-s[i].x)*(num-s[i].x)+s[i].y*s[i].y);

         if(q>ans)

         {

             ans=q;

         }

     }

     return ans;

 }

 int main()

 {

     cin >> n;

     int a,b;

     for(int i=; i<=n; i++)

     {

         cin >> a >> b;

         s[i].x=a;

         s[i].y=b;

     }

     double Left, Right;

     double mid, midmid;

     double mid_value, midmid_value;

     Left = -;

     Right = ;

     while (Left + EPS < Right)

     {

         mid = (Left + Right)/;

         midmid = (mid + Right)/;

         mid_value = Calc(mid);

         midmid_value = Calc(midmid);

         if (mid_value <= midmid_value)

             Right = midmid;

         else

             Left = mid;

     }

     cout << Calc(Left) << endl;

     return ;

 }