#include <bits/stdc++.h>
using namespace std;
const double pi = acos(-1.0);
const double eps = 1E-7;
int n, P1, P2, a[10005], b[10005];
int A, B, r1;
int main() {
  scanf("%d", &n);
  r1 = 0;
  for (int i = 1; i <= n; ++i) {
    int x;
    scanf("%d", &x);
    r1 = max(r1, x);
  }
  scanf("%d", &P1);
  for (int i = 1; i <= P1; ++i) scanf("%d", &a[i]);
  scanf("%d", &P2);
  for (int i = 1; i <= P2; ++i) scanf("%d", &b[i]);
  scanf("%d%d", &A, &B);
  double r2;
  for (int i = 1; i <= P1; ++i)
    for (int j = 1; j <= P2; ++j) {
      double tr2;
      tr2 = (double)(a[i] * B) / (double)(A * b[j] + a[i] * B);
      tr2 = sqrt(tr2);
      tr2 *= r1;
      r2 = max(tr2, r2);
    }
  printf("%.7lf\n", r2);
  return 0;
}
