#include<bits/stdc++.h>
#define N 1010
using namespace std;
int n;
double ansx,ansy,ans;
double totx=0,toty=0;
double t;
double delta=0.999;
struct node{
	double x,y,w;
};node f[N];
double check(double x,double y) {
	double dx,dy,ret=0;
	for(int i=1;i<=n;i++) {
		dx=x-f[i].x;
		dy=y-f[i].y;
		ret=max(sqrt(dx*dx+dy*dy),ret);
	}
	return ret;
}
void sa() {
	t=45000;
	while(t>1e-18) {
		double tx=ansx+(rand()*2-RAND_MAX)*t;
		double ty=ansy+(rand()*2-RAND_MAX)*t;
		double a=check(tx,ty);
		double an=a-ans;
//		printf("%lf %lf %lf\n",tx,ty,a);
		if(an<0) ansx=tx,ansy=ty,ans=a;
		else if(exp(-an/t)*RAND_MAX>rand()) ansx=tx,ansy=ty;
		t*=delta;
	}
}
int main() {
	srand(1960);
	scanf("%d",&n);
	for(int i=1;i<=n;i++) {
		cin>>f[i].x>>f[i].y;
		totx+=f[i].x;
		toty+=f[i].y; 
	}
	ansx=totx/n;
	ansy=toty/n;
	ans=check(ansx,ansy);
	for(int i=1;i<=10;i++) sa();
	double dx,dy,ret;
	for(int i=1;i<=n;i++) {
		dx=ansx-f[i].x;
		dy=ansy-f[i].y;
		ret=max(sqrt(dx*dx+dy*dy),ret);
	}
	cout<<fixed<<setprecision(7)<<ret;
	return 0;
}