#include <bits/stdc++.h>
#define For(i, a, b) for(int i = a; i <= b; i++)
#define F first
#define S second
#define all(x) x.begin(), x.end()
#define sz(x) ((int)x.size())
#define eb emplace_back
// #define int LL
#define double long double
using namespace std;
using LL = long long;
using pii = pair<int, int>;

int32_t main() {
    ios::sync_with_stdio(false);
    cin.tie(0);

    int n; cin >> n;
    vector<int> v(n);
    for(auto &i:v) cin >> i;
    double mn = 0;
    for(auto &i:v) mn = max(mn, (double)i / 2);
    double hi = 6e10, lo = mn;
    double tot = acos(-1) * 2;
    cout << fixed << setprecision(15);
    For(_, 1, 1000) {
        double mi = (hi + lo) / 2;
        double s = 0;
        for(auto &a:v) s += 2 * asin(a / mi / 2);
        // cout << mi << " " << s << "\n";
        if(s > tot) lo = mi;
        else hi = mi;
    }
    if(abs(hi - mn) <= 1e-5) {
        hi = 6e10; lo = mn;
        sort(all(v));
        int mxl = v.back(); v.pop_back();
        For(_, 1, 1000) {
            double mi = (hi + lo) / 2;
            double s = 0;
            double s2 = 2 * asin(mxl / mi / 2);
            for(auto &a:v) s += 2 * asin(a / mi / 2);
            if(s > s2) hi = mi;
            else lo = mi;
        }
    }
    cout << hi << "\n";
    return 0;
}