#include <bits/stdc++.h>
using namespace std;
int main() {
  double p1, p2, r2, r1, a, b;
  int n, m, d;
  cin >> n;
  double arr1[n];
  for (int i = 0; i < n; i++) {
    cin >> arr1[i];
  }
  sort(arr1, arr1 + n);
  r1 = arr1[n - 1];
  cin >> m;
  double arr2[m];
  for (int i = 0; i < m; i++) {
    cin >> arr2[i];
  }
  sort(arr2, arr2 + m);
  p1 = arr2[m - 1];
  cin >> d;
  double arr3[d];
  for (int i = 0; i < d; i++) {
    cin >> arr3[i];
  }
  sort(arr3, arr3 + d);
  p2 = arr3[0];
  cin >> a >> b;
  r2 = (double)sqrt((p1 / p2) / ((a / b) + (p1 / p2))) * r1;
  cout << setprecision(12) << fixed;
  cout << r2;
  return 0;
}
