#include <bits/stdc++.h>
using namespace std;
const int maxn = 6000;
const long double eps = 1e-10;
long long x[maxn], y[maxn], z[maxn];
int main() {
  int n, m, k, a, b;
  long long r1;
  cin >> n;
  for (int i = 0; i < n; ++i) cin >> x[i];
  r1 = x[0];
  for (int i = 1; i < n; ++i) r1 = max(r1, 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;
  long double ans = 0;
  for (int p1 = 0; p1 < m; ++p1)
    for (int p2 = 0; p2 < k; ++p2) {
      long double newans = (long double)r1 * r1 * y[p1] /
                           ((long double)y[p1] + (long double)a / b * z[p2]);
      if (newans - ans > eps) ans = newans;
    }
  cout.precision(20);
  cout << sqrt(ans);
  return 0;
}
