#include <bits/stdc++.h>
using namespace std;
const double eps = 1e-10;
int dblcmp(double d) {
  if (fabs(d) < eps) return 0;
  return (d > 0) ? 1 : -1;
}
int n, m, k;
double a, b;
const int N = 10000;
double p1[N], p2[N], r1[N];
int main() {
  cin >> n;
  for (int i = 0; i < n; ++i) cin >> r1[i];
  cin >> m;
  for (int i = 0; i < m; ++i) cin >> p1[i];
  cin >> k;
  for (int i = 0; i < k; ++i) cin >> p2[i];
  cin >> a >> b;
  sort(r1, r1 + n);
  sort(p1, p1 + m);
  sort(p2, p2 + k);
  printf("%.12lf\n",
         sqrt(r1[n - 1] * r1[n - 1] / (1.0 + a / b * p2[0] / p1[m - 1])));
}
