#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  double a, b, r1 = -1, p1 = -1, p2 = 1000000000, result;
  int i;
  double n, m, k, temp;
  cin >> n;
  for (i = 0; i < n; i++) {
    cin >> temp;
    r1 = max(r1, temp);
  }
  cin >> m;
  for (i = 0; i < m; i++) {
    cin >> temp;
    p1 = max(p1, temp);
  }
  cin >> k;
  for (i = 0; i < k; i++) {
    cin >> temp;
    p2 = min(p2, temp);
  }
  cin >> a >> b;
  result = r1 * (double(sqrt((b * p1 / (a * p2 + p1 * b)))));
  cout << fixed << setprecision(12) << result;
}
