#include <bits/stdc++.h>
using namespace std;
using i64 = int64_t;
using vi = vector<i64>;
using vvi = vector<vi>;

vi par;
int find(int x) {
    if (x == par[x]) return x;
    return par[x] = find(par[x]);
}

bool unite(int x, int y) {
    x = find(x);
    y = find(y);
    if (x == y) return true;
    par[x] = y;
    return false;
}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    cout.tie(nullptr);
    cout.setf(ios::fixed);
    cout.precision(10);
    int n;
    cin >> n;
    vi xs(n), ys(n);
    for (int i = 0; i < n; i++) {
        cin >> xs[i] >> ys[i];
    }

    par = vi(n);
    iota(par.begin(), par.end(), 0);
    for (int i = 0; i < n; i++) {
        for (int j = i + 1; j < n; j++) {
            i64 d = i64(xs[i] - xs[j]) * (xs[i] - xs[j]) + i64(ys[i] - ys[j]) * (ys[i] - ys[j]);
            if (d <= 10 * 10) {
                unite(i, j);
            }
        }
    }

    map<int, i64> parXmin, parXmax, parYmin, parYmax;
    for (int i = 0; i < n; i++) {
        int p = par[i];
        if (parXmin.count(p) == 0) {
            parXmin[p] = xs[i];
            parXmax[p] = xs[i];
            parYmin[p] = ys[i];
            parYmax[p] = ys[i];
        } else {
            parXmin[p] = min(parXmin[p], xs[i]);
            parXmax[p] = max(parXmax[p], xs[i]);
            parYmin[p] = min(parYmin[p], ys[i]);
            parYmax[p] = max(parYmax[p], ys[i]);
        }
    }

    double ans = 1;
    for (auto& p: parXmin) {
        ans = max(ans, hypot(parXmax[p.first] - parXmin[p.first], parYmax[p.first] - parYmin[p.first]) + 2);
    }
    cout << ans << endl;
}