#include <bits/stdc++.h>
using namespace std;
double r1[5005], p1[5005], p2[5005];
int main() {
  int n, m;
  double a, b;
  double mx = -1;
  scanf("%d", &n);
  for (int i = 0; i < n; i++) {
    scanf("%lf", &r1[i]);
    if (r1[i] > mx) mx = r1[i];
  }
  scanf("%d", &n);
  for (int i = 0; i < n; i++) scanf("%lf", &p1[i]);
  scanf("%d", &m);
  for (int j = 0; j < m; j++) scanf("%lf", &p2[j]);
  double mx2 = -1;
  scanf("%lf%lf", &a, &b);
  double x;
  x = a / b;
  for (int i = 0; i < n; i++)
    for (int j = 0; j < m; j++) {
      double tmp;
      tmp = p1[i] / (x * p2[j] + p1[i]);
      if (tmp > mx2) mx2 = tmp;
    }
  printf("%lf", mx * sqrt(mx2));
  return 0;
}
