#include <bits/stdc++.h>
using namespace std;
int n, m, k, tmp, A, B;
vector<int> x, y, z;
int main() {
  cin >> n;
  for (int i = 0; i < n; i++) cin >> tmp, x.push_back(tmp);
  cin >> m;
  for (int i = 0; i < m; i++) cin >> tmp, y.push_back(tmp);
  cin >> k;
  for (int i = 0; i < k; i++) cin >> tmp, z.push_back(tmp);
  cin >> A >> B;
  double r1 = *max_element(x.begin(), x.end());
  double p1 = *max_element(y.begin(), y.end());
  double p2 = *min_element(z.begin(), z.end());
  cout.precision(24);
  cout << r1 * sqrt((B * p1) / (B * p1 + A * p2)) << endl;
  cin >> n;
  return 0;
}
