#include <bits/stdc++.h>
using namespace std;
int main(int argc, char *argv[]) {
  int n;
  cin >> n;
  int x, r1;
  r1 = 0;
  for (int i = (int)0; i < (int)n; i++) {
    cin >> x;
    if (x > r1) r1 = x;
  }
  int m;
  cin >> m;
  int y, p1;
  p1 = 0;
  for (int i = (int)0; i < (int)m; i++) {
    cin >> y;
    if (y > p1) p1 = y;
  }
  int k;
  cin >> k;
  int z, p2;
  p2 = 5001;
  for (int i = (int)0; i < (int)k; i++) {
    cin >> z;
    if (z < p2) p2 = z;
  }
  int a, b;
  cin >> a >> b;
  double r2;
  r2 = 1.0 * b * p1 * r1 * r1 / (a * p2 + b * p1);
  printf("%.12f", sqrt(r2));
  return 0;
}
