#include <stdio.h>
#include <bits/stdc++.h>
#include <atcoder/all>
using namespace atcoder;
using mint = modint998244353;
using namespace std;
#define rep(i,n) for (int i = 0; i < (n); ++i)
#define Inf 1000000001

int main(){
	
	int n;
	cin>>n;
	
	dsu D(n);
	vector<int> x(n),y(n);
	rep(i,n)cin>>x[i]>>y[i];
	
	rep(i,n){
		rep(j,n){
			if((x[i]-x[j])*(x[i]-x[j]) + (y[i]-y[j])*(y[i]-y[j]) <= 100)D.merge(i,j);
		}
	}
	double ans = 1.0;
	rep(i,n){
		rep(j,n){
			if(D.same(i,j)){
				ans = max(ans,2.0 + hypot(x[i]-x[j],y[i]-y[j]));
			}
			
		}
	}
	cout<<fixed<<setprecision(10)<<ans<<endl;
	
	return 0;
}