#include <bits/stdc++.h>
using namespace std;
int main() {
  int i, j, k, n, r1, p1, p2, temp, a, b;
  double ans;
  cin >> n;
  for (i = 1; i <= n; i++) {
    cin >> k;
    if (i == 1)
      r1 = k;
    else {
      r1 = ((r1) > (k) ? (r1) : (k));
    }
  }
  cin >> n;
  for (i = 1; i <= n; i++) {
    cin >> k;
    if (i == 1)
      p1 = k;
    else {
      p1 = ((p1) > (k) ? (p1) : (k));
    }
  }
  cin >> n;
  for (i = 1; i <= n; i++) {
    cin >> k;
    if (i == 1)
      p2 = k;
    else {
      p2 = ((p2) < (k) ? (p2) : (k));
    }
  }
  cin >> a >> b;
  ans = 1.0 * r1 / pow(1 + 1.0 * p2 * a / p1 / b, 0.5);
  printf("%.6lf", ans);
  return 0;
}
