#include <bits/stdc++.h>
using namespace std;

using VI = vector<int>;
using VVI = vector<VI>;
using PII = pair<int, int>;
using LL = long long;
using VL = vector<LL>;
using VVL = vector<VL>;
using PLL = pair<LL, LL>;
using VS = vector<string>;

#define ALL(a)  begin((a)),end((a))
#define RALL(a) (a).rbegin(), (a).rend()
#define PB push_back
#define EB emplace_back
#define MP make_pair
#define SZ(a) int((a).size())
#define SORT(c) sort(ALL((c)))
#define RSORT(c) sort(RALL((c)))
#define UNIQ(c) (c).erase(unique(ALL((c))), end((c)))

#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define REP(i,n)  FOR(i,0,n)

#define FF first
#define SS second
template<class S, class T>
istream& operator>>(istream& is, pair<S,T>& p){
  return is >> p.FF >> p.SS;
}
template<class S, class T>
ostream& operator<<(ostream& os, const pair<S,T>& p){
  return os << p.FF << " " << p.SS;
}
template<class T>
void maxi(T& x, T y){
  if(x < y) x = y;
}
template<class T>
void mini(T& x, T y){
  if(x > y) x = y;
}


const double EPS = 1e-10;
const double PI  = acos(-1.0);
const LL MOD = 1e9+7;

int main(){
  cin.tie(0);
  ios_base::sync_with_stdio(false);

  int N;
  cin >> N;
  VL evs, ods;
  REP(i,N){
	LL x;
	cin >> x;
	if(x % 2 == 0) evs.EB(x);
	else ods.EB(x);
  }
  SORT(ods);
  SORT(evs);
  LL dx, dy;
  cin >> dx >> dy;
  LL s = abs(dx) + abs(dy);

  if(s == 0){
	cout << 0 << endl;
	return 0;
  }
  
  if(count(ALL(ods), s) || count(ALL(evs), s)){
	cout << 1 << endl;
	return 0;
  }

  if(s % 2 == 1){
	for(LL e: evs){
	  auto it = lower_bound(ALL(ods), s - 3*e);
	  if(it != end(ods) && *it <= s-e){
		cout << 2 << endl;
		return 0;
	  }
	}
	for(LL o: ods){
	  auto it = lower_bound(ALL(evs), s - 3*o);
	  if(it != end(evs) && *it <= s-o){
		cout << 2 << endl;
		return 0;
	  }
	}
  }
  else{
	for(LL e: evs){
	  auto it = lower_bound(ALL(evs), s - 3*e);
	  if(it != end(evs) && *it <= s-e){
		cout << 2 << endl;
		return 0;
	  }
	}
	for(LL o: ods){
	  auto it = lower_bound(ALL(ods), s - 3*o);
	  if(it != end(ods) && *it <= s-o){
		cout << 2 << endl;
		return 0;
	  }
	}
  }
  
  cout << -1 << endl;

  return 0;
}