#include #include #include #include #include #include #include #define rep(i, n) for(i = 0; i < (n); i++) #define chmax(x, y) x = max(x, y) #define chmin(x, y) x = min(x, y) #define MOD 1000000007 #define PI 3.14159265358979323846 #define INF 1 << 30 using namespace std; typedef long long ll; typedef pair pp; double Search(double l, double r, const ll k, vector & d) { if (r - l < 0.00000001) return l; double p = (l + r) / 2.0; ll i, sum = 0; rep(i, d.size()) sum += floor(d[i] / p); if (sum >= k) return Search(p, r, k, d); else return Search(l, p, k, d); } int main(void) { int num, i; ll k; double ans, ma = 0; cin >> num; vector d(num); rep(i, num) { cin >> d[i]; chmax(ma, d[i]); } cin >> k; ans = Search(0.0, ma, k, d); printf("%.15lf\n", ans); return 0; }