#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, m, k;
  int x[5001], y[5001], z[5001];
  scanf("%d", &n);
  double mx = -10;
  for (int i = 0; i < n; i++) {
    scanf("%d", x + i);
    mx = max(mx, x[i] * 1.0);
  }
  scanf("%d", &m);
  for (int i = 0; i < m; i++) scanf("%d", y + i);
  scanf("%d", &k);
  for (int i = 0; i < k; i++) scanf("%d", z + i);
  double A, B;
  scanf("%lf %lf", &A, &B);
  double mn = 2e9 * 1.0;
  for (int j = 0; j < m; j++) {
    for (int l = 0; l < k; l++) {
      mn = min((A * z[l] * 1.0) / (B * y[j] * 1.0), mn);
    }
  }
  printf("%.10f\n", mx * 1.0 / sqrt(1.0 + mn));
}
