#include <iostream>
#include <algorithm>
#include <vector>

using namespace std;

int main() {
  int n;
  cin >> n;

  vector<int> d(n);
  for (int i = 0; i < n; i++) {
    cin >> d[i];
  }

  int x, y;
  cin >> x >> y;

  if (x == 0 && y == 0) {
    cout << 0 << endl;
    return 0;
  }

  for (int i = 0; i < n; i++) {
    if (abs(x) + abs(y) == d[i]) {
      cout << 1 << endl;
      return 0;
    }
  }

  for (int i = 0; i < n; i++) {
    if (abs(x) + abs(y) <= 2 * d[i]) {
      cout << 2 << endl;
      return 0;
    }
  }

  cout << -1 << endl;
}