#include <bits/stdc++.h>
#define sz(x) signed(size(x))
using namespace std;
using ll = long long;
using LL = long long;
using ld = long double;

inline void solve() {
    int n;
    cin >> n;
    
    vector<int> a(n);
    for (int& i : a)
        cin >> i;


    ld l = 0, r = 10000001;
    while (r - l > 1e-10) {
        ld mid = (l + r) / 2;
        
        ld sum = 0, mx = 0;
        for (int i = 0; i < n; ++i) {
            ld th = 1.0 -  (ld)a[i] * a[i] / 2 / mid / mid;
            if (a[i] + 1e-10 > mid + mid) {
                sum = 1e9;
                break;
            }

            mx = max(mx, acosl(th));
            sum += acosl(th);
        }
    

        if (sum < 2 * M_PI){
            if(mx > sum - mx){
                l  = mid;
                continue;
            }
            r = mid;
        }
        else
            l = mid;
    }

    cout << fixed << setprecision(13) << r << '\n';
}

signed main() {
    cin.tie(0)->sync_with_stdio(0);
    int t = 1;
    while (t--)
        solve();
    return 0;
}