#include <bits/stdc++.h>

using namespace std;
using ll = long long;
using PII = std::pair<int, int>;
using PLL = std::pair<ll, ll>;

#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define rep2(i, s, n) for (int i = (s); i < (int)(n); i++)


struct point
{
    int x;
    int y;
};

class Unionfind
{
    vector<int> p;

public:
    int find(int x);
    void unite(int x, int y);
    Unionfind(int n);
};

Unionfind::Unionfind(int n)
{
    for (int i = 0; i < n; i++)
    {
        p.push_back(i);
    }
}
int Unionfind::find(int x)
{
    while (p[x] != x)
    {
        p[x] = p[p[x]];
        x = p[x];
    }
    return x;
}

void Unionfind::unite(int x, int y)
{
    x = Unionfind::find(x);
    y = Unionfind::find(y);
    if (x != y)
    {
        p[x] = y;
    }
}

int main()
{

#ifdef DEBUG
    cout << "DEBUG MODE" << endl;
    ifstream in("input.txt"); //for debug
    cin.rdbuf(in.rdbuf());    //for debug
#endif

    int n, x, y, d, maxdist;
    cin >> n;
    double maxdist2;

    Unionfind tower(n);
    point towerxy[n];
    rep(i, n)
    {
        cin >> x >> y;
        towerxy[i].x = x;
        towerxy[i].y = y;
    }

    rep(i, n - 1)
    {
        rep2(j, i + 1, n)
        {
            d = pow(towerxy[i].x - towerxy[j].x, 2) + pow(towerxy[i].y - towerxy[j].y, 2);
            if (d <= 100)
                tower.unite(i, j);
        }
    }
    maxdist = 0;
    rep(i, n - 1)
    {
        rep2(j, i + 1, n)
        {
            if (tower.find(i) == tower.find(j)){
                d = pow(towerxy[i].x - towerxy[j].x, 2) + pow(towerxy[i].y - towerxy[j].y, 2);
                maxdist = max(maxdist, d);
            }
        }
    }


    if (n == 0)
    {
        cout << 1 << endl;
    }
    else
    {
        printf( "%.8f\n", sqrt(1.0 * maxdist) + 2.0 );
    }
    
    return 0;
}