#include <bits/stdc++.h>
using namespace std;;
using ll = long long;
using ull = unsigned long long;
using ld = long double;
using uint = unsigned int;
const double EPS = 1e-10;
const int INF = 0x3F3F3F3F;
const ll LINF = 46 * ll(1e17);
const int MOD = 1e9 + 7;
const int maxn = 1e5 + 25;

signed main() { ios::sync_with_stdio(0); cin.tie(0);
    int n;
    cin >> n;
    vector<int> arr(n);
    for (int &a : arr)
        cin >> a;
    auto check = [&] (double r) {
        double theta = 0;
        for (int x : arr) {
            double cur_cos = (2 * r * r - x * x) / (2 * r * r);
            theta += acos(cur_cos);
        }
        return theta;
    };
    auto check2 = [&] (double r) {
        double theta = 0, mx = 0;
        for (int x : arr) {
            double cur_cos = (2 * r * r - x * x) / (2 * r * r);
            double ac = acos(cur_cos);
            theta += ac;
            mx = max(mx, ac);
        }
        // cerr << r << ' ' << theta << ' ' << mx << '\n';
        return theta < 2 * mx;
    };
    int mx = *max_element(arr.begin(), arr.end());
    const double PI = acos(-1);
    double l = double(mx) / 2, r = 1e7;
    while (r - l > EPS) {
        double m = (l + r) / 2;
        if (check(m) > 2 * PI)
            l = m;
        else
            r = m;
    }

    cout << fixed << setprecision(15);
    if (check(l) < 2 * PI && abs(2 * PI - check(l)) > EPS)
        ;
    else {
        cout << l << '\n';
        return 0;
    }

    l = double(mx) / 2, r = 1e7;
    while (r - l > EPS) {
        double m = (l + r) / 2;
        if (check2(m))
            l = m;
        else
            r = m;
    }
    cout << l << '\n';
}