#include <bits/stdc++.h>
using namespace std;

#ifdef DEBUG
#define fast
#else
#define fast cin.tie(0)->sync_with_stdio(0)
#define cerr if(1);else cerr
#define endl '\n'
#endif
#define _ <<' '<<
#define ALL(v) v.begin(),v.end()
#define ft first
#define sd second

using ll = long long;
using ld = long double;
using pii = pair<int,int>;
const ld eps = 1e-10;
constexpr ld pi = acos(-1);
signed main() {
    fast;

    int n;
    cin>>n;
    vector<ld> arr(n);
    for(int i=0;i<n;i++)
    {
        cin>>arr[i];
    }
    sort(arr.begin(), arr.end());

    auto sana=[&](ld r, bool x)
    {
        ld sum=0;
        for(ld x:arr)
        {
            sum+=asin(x/2/r)*2;
        }
        if (x) {
            ld l = asin(arr.back()/2/r)*2;
            sum = sum-l*2+2*pi;
        }
        // cerr _ r _ sum _ endl;
        return sum;
    };

    ld l=arr.back()/2, r=l*n;
    cerr _ l _ r _ endl;
    while(l+eps<r)
    {
        ld m=(l+r)/2;
        if(sana(m,0)<2*pi)
            r=m;
        else
            l=m;
    }
    ld al = l;

    l=arr.back()/2, r=l*2*n;
    cerr _ l _ r _ endl;
    while(l+eps<r)
    {
        ld m=(l+r)/2;
        if(sana(m,1) > 2*pi)
            r=m;
        else
            l=m;
    }
    ld bl = l;

    cerr _ al _ bl _ endl;

    ld ans;
    if (abs(sana(al,0) - 2*pi) < abs(sana(bl,1) - 2*pi))
        ans = al;
    else
        ans = bl;
    cout<<fixed<<setprecision(10)<<ans<<endl;

    return 0;
}