// includes #include // macros #define ll long long int #define pb emplace_back #define mk make_pair #define pq priority_queue #define FOR(i, a, b) for(int i=(a);i<(b);++i) #define rep(i, n) FOR(i, 0, n) #define rrep(i, n) for(int i=((int)(n)-1);i>=0;i--) #define all(x) (x).begin(),(x).end() #define sz(x) ((int)(x).size()) #define UNIQUE(v) v.erase(unique(v.begin(), v.end()), v.end()) #define FI first #define SE second using namespace std; // types typedef pair P; typedef pair Pl; typedef pair Pll; typedef pair Pd; // constants const int inf = 1e9; const ll linf = 1LL << 50; const double EPS = 1e-10; const int mod = 1e9 + 7; // solve template bool chmax(T &a, const T &b){if(a < b){a = b; return 1;} return 0;} template bool chmin(T &a, const T &b){if(a > b){a = b; return 1;} return 0;} template istream &operator>>(istream &is, vector &vec){for(auto &v: vec)is >> v; return is;} int main(int argc, char const* argv[]) { ios_base::sync_with_stdio(false); cin.tie(0); int n; cin >> n; vector l(n); cin >> l; ll k; cin >> k; double ld = 0., rd = 1e9 + 1; while(rd - ld > EPS * ld){ double md = (rd + ld) / 2; ll s = 0; for(int i = 0; i < n; i++)s += (ll)(l[i] / md); if(s >= k)ld = md; else rd = md; } cout << setprecision(20); cout << ld << endl; return 0; }