#include <bits/stdc++.h>
using namespace std;
const long long INF = 1e18;
long long int small = INT_MIN;
long long int large = INT_MAX;
void solve() {
  long long int k;
  cin >> k;
  double maxr1 = small;
  for (long long int i = 0; i < k; i++) {
    double t;
    cin >> t;
    maxr1 = max(maxr1, t);
  }
  long long int n;
  cin >> n;
  double maxp1 = small;
  for (long long int i = 0; i < n; i++) {
    double t;
    cin >> t;
    maxp1 = max(maxp1, t);
  }
  long long int m;
  cin >> m;
  double minp2 = large;
  for (long long int i = 0; i < m; i++) {
    double t;
    cin >> t;
    minp2 = min(minp2, t);
  }
  long long int a, b;
  cin >> a >> b;
  double ans = double((a * minp2) / (b * maxp1));
  ans += 1;
  ans = sqrt(ans);
  ans = maxr1 / ans;
  cout.precision(12);
  cout << fixed;
  cout << ans;
}
signed main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  long long int T = 1;
  while (T--) solve();
  return 0;
}
