#include <bits/stdc++.h>
using namespace std;
const int maxn =50005; 
struct node{
	int score1,score2,score3;
}a[maxn];
bool cmp(node c,node b)
{
	return c.score3>b.score3;
 } 
int main() {
	
	int n;
	cin>>n;
	for(int i=1;i<=n;i++)
	{
		cin>>a[i].score1>>a[i].score2>>a[i].score3;
		
	}
	
	sort(a+1,a+1+n,cmp);
	double sum=sqrt(pow(a[1].score1-a[n].score1,2)+pow(a[1].score2-a[n].score2,2)+pow(a[1].score3-a[n].score3,2));
	cout<<fixed<<setprecision(3)<<sum;
}