#include <bits/stdc++.h>
using namespace std;
int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  int n, r1 = -1, p1 = -1, p2 = INT_MAX, x, a, b;
  cin >> n;
  while (n--) cin >> x, r1 = max(r1, x);
  cin >> n;
  while (n--) cin >> x, p1 = max(p1, x);
  cin >> n;
  while (n--) cin >> x, p2 = min(p2, x);
  cin >> a >> b;
  long double q = ((long long)(b * p1) / (long double)(a * p2 + b * p1));
  q = sqrt(q);
  q *= r1;
  printf("%.12Lf\n", q);
  return 0;
}
