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


template <class F> class y_combinator {
    F f;

   public:
    y_combinator(F&& f) : f(std::forward<F>(f)) {}
    template <class... Args> auto operator()(Args&&... args) const { return f(*this, std::forward<Args>(args)...); }
};

constexpr int dx[8] = {1, 0, -1, 0, 1, 1, -1, -1};
constexpr int dy[8] = {0, 1, 0, -1, 1, -1, 1, -1};

using ll = long long;
using u32 = unsigned int;
using u64 = unsigned long long;

using vi = vector<int>;
using vl = vector<ll>;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
template <class T> using vc = vector<T>;
template <class T> using vvc = vector<vc<T>>;
template <class T, class U = std::less<T>> using prique = priority_queue<T, vector<T>, U>;

#define overload(a, b, c, d, e, ...) e
#define len(x) (ll)(x.size())
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
#define rep1(n) for (ll _ = 0; _ < ll(n); _++)
#define rep2(i, n) for (ll i = 0; i < ll(n); i++)
#define rep3(i, a, b) for (ll i = ll(a); i < ll(b); i++)
#define rep4(i, a, b, c) for (ll i = ll(a); i < ll(b); i += ll(c))
#define rep(...) overload(__VA_ARGS__, rep4, rep3, rep2, rep1)(__VA_ARGS__)
#define rrep(i, n) for (ll i = ll(n) - 1; i >= 0; i--)

template <class T = ll, class U> vector<T> cumsum(const vector<U>& a) { vector<T> res(a.size() + 1); rep(i, a.size()) res[i + 1] = res[i] + a[i]; return res; }
template <class T> void dedup(vector<T>& a) { sort(all(a)), a.erase(unique(all(a)), a.end()); }
template <class T> bool chmax(T& a, const T& b) { return a < b ? a = b, 1 : 0; }
template <class T> bool chmin(T& a, const T& b) { return a > b ? a = b, 1 : 0; }

namespace cppio {

template <typename T> struct is_tuple_like : false_type {};
template <typename... Ts> struct is_tuple_like<tuple<Ts...>> : true_type {};
template <typename T, typename U> struct is_tuple_like<pair<T, U>> : true_type {};
template <typename T, typename = void> struct is_container : false_type {};
template <typename T> struct is_container<T, void_t<decltype(begin(declval<T&>()))>> : bool_constant<!is_same_v<decay_t<T>, string> && !is_same_v<decay_t<T>, char*> && !is_same_v<decay_t<T>, const char*> && !is_array_v<remove_reference_t<T>>> {};
template <typename T> void _in(T& x) { if constexpr (is_tuple_like<T>::value) apply([](auto&... elems) { (_in(elems), ...); }, x); else if constexpr (is_container<T>::value) { for (auto& e : x) _in(e); } else cin >> x; }
template <typename... Ts> void _in_all(Ts&... args) { (_in(args), ...); }
template <typename T> void _out(const T& x) { bool first = true; if constexpr (is_tuple_like<T>::value) { apply([&](const auto&... elems) { ((cout << (first ? "" : " "), _out(elems), first = false), ...); }, x); } else if constexpr (is_container<T>::value) { for (const auto& e : x) { if (!first) cout << ' '; _out(e), first = false; } } else cout << x; }
template <typename... Ts> void _print(const Ts&... args) { bool first = true; ((cout << (first ? "" : " "), _out(args), first = false), ...); }
template <typename... Ts> void _out_all(const Ts&... args) { _print(args...), cout << '\n'; }

}  // namespace cppio

#define IN(...) cppio::_in_all(__VA_ARGS__)
#define OUT(...) cppio::_out_all(__VA_ARGS__)

#define INT(...) int __VA_ARGS__; IN(__VA_ARGS__)
#define LL(...)  ll __VA_ARGS__; IN(__VA_ARGS__)
#define STR(...) string __VA_ARGS__; IN(__VA_ARGS__)
#define CHR(...) char __VA_ARGS__; IN(__VA_ARGS__)
#define DBL(...) double __VA_ARGS__; IN(__VA_ARGS__)
#define VEC(type, name, size) vector<type> name(size); IN(name)
#define VV(type, name, h, w)  vector<vector<type>> name(h, vector<type>(w)); IN(name)
#define RETURN(...) do { __VA_ARGS__; return; } while (0)

bool Yes(bool b = true) { return OUT(b ? "Yes" : "No"), b; }
bool No(bool b = true) { return Yes(!b), b; }
bool YES(bool b = true) { return OUT(b ? "YES" : "NO"), b; }
bool NO(bool b = true) { return YES(!b), b; }

#ifdef ONLINE_JUDGE
#define debug(...) (void(0))
#endif

void run_case() {
    LL(N);
    VEC(ll, D, N);
    LL(X, Y);
    if (X == 0 && Y == 0) RETURN(OUT(0));
    {
        ll x = X + Y, y = X - Y;
        X = x, Y = y;
    }

    map<ll, pll> x0, y0;
    rep(i, N) x0[D[i]] = x0[-D[i]] = y0[D[i]] = y0[-D[i]] = {-D[i], D[i]};

    map<ll, pll> xn, yn;
    rep(i, N) xn[X + D[i]] = xn[X - D[i]] = {Y - D[i], Y + D[i]}, y0[Y + D[i]] = y0[Y - D[i]] = {X - D[i], X + D[i]};
    bool ok = false;
    if (x0.find(X) != x0.end() && x0[X].first <= Y && Y <= x0[X].second) {
        RETURN(OUT(1));
    }
    for (auto [x, yp] : x0) {
        auto [l, r] = yp;
        if (xn.find(x) != xn.end()) {
            auto [ll, rr] = xn[x];
            if (max(l, ll) <= min(r, rr)) {
                ok = true;
            }
        }
    }
    for (auto [y, xp] : y0) {
        auto [l, r] = xp;
        if (yn.find(y) != yn.end()) {
            auto [ll, rr] = yn[y];
            if (max(l, ll) <= min(r, rr)) {
                ok = true;
            }
        }
    }
    if(ok) OUT(2);
    else OUT(-1);
}
int main() {
    std::ios_base::sync_with_stdio(false);
    std::cin.tie(nullptr);
    std::fixed(std::cout).precision(16);
    int t = 1;
    while (t--) run_case();
}