#include <iostream>
#include <iomanip>
#include <vector>
#include <cmath>
using namespace std;

struct Point {
    int x, y;

    Point(): x(0),y(0) {};
    Point(int a, int b): x(a), y(b) {};

    Point operator -(const Point& p) {
        return Point(x - p.x, y - p.y);
    }

    float distance() {
        return sqrt(x * x + y * y);
    }
};

int main()
{
    int n, a, b;
    cin >> n;
    double maxim = 0;
    vector <Point> pnt (n);
    for (int i = 0; i < n; ++i)
    {
        cin >> a >> b;
        pnt[i] = Point(a, b);
    }
    for (int i = 0; i < n; ++i)
    {
        for (int j = i + 1; j < n; ++j)
        {
            float d = (pnt[i] - pnt[j]).distance();
            if (d > maxim)
                maxim = d;
        }
    }
    cout << setprecision(15) << maxim;
}