#include #include #include #include #include #include #include #include #include #include #include #include #include using namespace std; int main() { int n; cin >> n; vector l(n); for (int i = 0; i < n; i++) cin >> l[i]; long long k; cin >> k; double ok = 0; double ng = 1e10; for (int j = 0; j < 100; j++) { double x = (ok+ng)/2.0; long long cnt = 0; for (int i = 0; i < n; i++) cnt += l[i]/x; //cout << "x = " << x << ", cnt = " << cnt << endl; if (cnt >= k) ok = x; else ng = x; } printf("%.15llf\n", ok); }