#include <bits/stdc++.h>
using namespace std;
const int NAX = 5000;
int main() {
  int n, x[NAX], m, y[NAX], k, z[NAX], A, B;
  cin >> n;
  for (int i = 0; i < n; ++i) cin >> x[i];
  cin >> m;
  for (int i = 0; i < m; ++i) cin >> y[i];
  cin >> k;
  for (int i = 0; i < k; ++i) cin >> z[i];
  cin >> A >> B;
  sort(z, z + k);
  int p2 = z[0];
  double ans = 0;
  for (int i = 0; i < n; ++i) {
    for (int j = 0; j < m; ++j) {
      double temp = sqrt((pow(x[i], 2) * y[j] * B) / (A * p2 + B * y[j]));
      ans = max(ans, temp);
    }
  }
  printf("%.10f", ans);
  return 0;
}
