#include <bits/stdc++.h>
using namespace std;
int r1[5001], p1[5001], p2[5001];
int main() {
  int i, j, n, m, k, a, b;
  cin >> n;
  for (i = 0; i < n; i++) cin >> r1[i];
  cin >> m;
  for (i = 0; i < m; i++) cin >> p1[i];
  cin >> k;
  for (i = 0; i < k; i++) cin >> p2[i];
  cin >> a >> b;
  float sid = (float)a / (float)b;
  int P1, P2, R1;
  P1 = *max_element(p1, p1 + m);
  P2 = *min_element(p2, p2 + k);
  R1 = *max_element(r1, r1 + n);
  float ans;
  ans = ((float)R1 * (float)R1) / (((float)P2 / (float)P1) * sid + 1);
  ans = sqrt(ans);
  printf("%0.10f\n", ans);
  return 0;
}
