#define HAVE_STRUCT_TIMESPEC
#include<bits/stdc++.h>
using namespace std;
double x[1007],y[1007];
double X,Y,d,e,P=0.1;
int main(){
    int n;
	scanf("%d",&n);
	for(int i=0;i<n;++i){
		scanf("%lf%lf",&x[i],&y[i]);
		X+=x[i];
		Y+=y[i];
	}
	X/=n;
	Y/=n;
	for(int i=0;i<30000;++i){
		int f=0;
		d=(X-x[0])*(X-x[0])+(Y-y[0])*(Y-y[0]);
		for(int j=1;j<n;++j){
			e=(X-x[j])*(X-x[j])+(Y-y[j])*(Y-y[j]);
			if(d<e)
                d=e,f=j;
		}
		X+=(x[f]-X)*P;
		Y+=(y[f]-Y)*P;
		P*=0.999;
	}
	printf("%.10lf",sqrt(d));
}
