#include <bits/stdc++.h>
int x[5005], y[5005], z[5005], i, j, k, n, m;
double u, max;
void init() {
  int a, b;
  scanf("%d", &n);
  max = 0;
  for (i = 0; i < n; i++) {
    scanf("%d", x + i);
    if (x[i] > max) max = x[i];
  }
  scanf("%d", &m);
  for (i = 0; i < m; i++) scanf("%d", y + i);
  scanf("%d", &k);
  for (i = 0; i < k; i++) scanf("%d", z + i);
  scanf("%d%d", &a, &b);
  u = double(a) / b;
}
void solve() {
  int i, j;
  double ans, maxx;
  maxx = 0;
  for (i = 0; i < m; i++)
    for (j = 0; j < k; j++) {
      ans = y[i] * max * max / (u * z[j] + y[i]);
      if (ans > maxx) maxx = ans;
    }
  maxx = sqrt(maxx);
  printf("%lf\n", maxx);
}
int main() {
  init();
  solve();
  return 0;
}
