#include <iostream>
#include <cmath>
#include <vector>
#include <algorithm>
using namespace std;
 
int main() {
	int N;
	cin >> N;
	int ara[N][2];
	for(int i=0; i<N; i++){
		for(int j=0; j<2; j++){
			cin >> ara[i][j];
		}
	}
 
	vector<double>v;
	for(int a=0; a<N; a++){
		for(int b=0; b<N; b++){
			if(a!=b){
				int m, n;
				m = abs(ara[a][0] - ara[b][0]);
				n = abs(ara[a][1] - ara[b][1]);
				double len = sqrt(m*m + n*n);
				v.push_back(len);
			}
		}
	}
	sort(v.rbegin(), v.rend());
	cout << v[0] << endl;
 
	return 0;
}

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3
0 0
0 1
1 1