三分

#include <iostream>

#include <cmath>

#include <iomanip>

#define ios ios::sync_with_stdio(0);cin.tie(0);cout.tie(0)

#define endl '\n'

using namespace std;

const int N=1e3+100;

const double eps=1e-5;

int n;

int a[N],b[N];

double getdis(double x,double y){

	double res=0;

	for(int i=1;i<=n;i++) res+=sqrt(pow(x-a[i],2)+pow(y-b[i],2));

	return res;

}

double work(double x){

	double l=0,r=10000,lmid,rmid;

	while(r-l>eps){

		lmid=l+(r-l)/3;

		rmid=r-(r-l)/3;

		if(getdis(x,lmid)>getdis(x,rmid)) l=lmid;

		else r=rmid;

	}

	return getdis(x,lmid);

}

int main()

{

	ios;

	cin>>n;

	for(int i=1;i<=n;i++) cin>>a[i]>>b[i];

	double l=0,r=10000,lmid,rmid;

	while(r-l>eps){

		lmid=l+(r-l)/3;

		rmid=r-(r-l)/3;

		if(work(lmid)>work(rmid)) l=lmid;

		else r=rmid;

	}

	cout<<fixed<<setprecision(0)<<work(l)<<endl;

	return 0;

}