#include <bits/stdc++.h>
using namespace std;
int calc(int x1,int y1,int x2,int y2){
	return (x1-x2)*(x1-x2)+(y1-y2)*(y1-y2);
}

int main(){
	int n;	cin>>n;
	int x[n],y[n];
	for(int i=0;i<n;i++)	cin>>x[i]>>y[i];
	int longest=0,num=0;
	for(int i=1;i<n;i++){
		if(longest<calc(x[0],y[0],x[i],y[i])){
			longest=calc(x[0],y[0],x[i],y[i]);
			num=i;
		}
	}
	int next=0;
	for(int i=1;i<n;i++){
		if(i==num)	continue;
		if(longest<calc(x[num],y[num],x[i],y[i])){
			next=i;
			longest=calc(x[num],y[num],x[i],y[i]);
		}
	}
	printf("%lf.15\n",(double)2+sqrt(calc(x[num],y[num],x[next],y[next])));
	return 0;
}