#include <bits/stdc++.h>

#define VARNAME(x) #x
#define show(x) cerr << #x << " = " << x << endl

using namespace std;
using ll = long long;

template <typename T>
ostream& operator<<(ostream& os, const vector<T>& v)
{
    os << "sz:" << v.size() << "\n[";
    for (const auto& p : v) {
        os << p << ",";
    }
    os << "]\n";
    return os;
}

template <typename S, typename T>
ostream& operator<<(ostream& os, const pair<S, T>& p)
{
    os << "(" << p.first << "," << p.second
       << ")";
    return os;
}


constexpr ll MOD = (ll)1e9 + 7LL;

template <typename T>
constexpr T INF = numeric_limits<T>::max() / 64;

using P = pair<ll, ll>;
P convert(const P& pos)
{
    const ll x = pos.first - pos.second;
    const ll y = pos.first + pos.second;
    return make_pair(x, y);
}

int main()
{
    int N;
    cin >> N;
    vector<ll> d(N);
    for (int i = 0; i < N; i++) {
        cin >> d[i];
    }
    ll x, y;
    cin >> x >> y;
    if (x == 0 and y == 0) {
        cout << 0 << endl;
    }
    for (int i = 0; i < N; i++) {
        if (abs(x) + abs(y) == d[i]) {
            cout << 1 << endl;
            return 0;
        }
    }
    sort(d.begin(), d.end());
    tie(x, y) = convert(make_pair(x, y));
    for (int i = 0; i < N; i++) {
        const ll xinf = x - d[i];
        const ll yinf = y - d[i];
        const ll xsup = x + d[i];
        const ll ysup = y + d[i];
        for (int j = 0; j < 4; j++) {
            const ll mini = (j == 0) ? min({abs(yinf), abs(xinf), abs(xsup)}) : (j == 1) ? min({abs(xinf), abs(yinf), abs(ysup)}) : (j == 2) ? min({abs(ysup), abs(xinf), abs(xsup)}) : min({abs(xsup), abs(yinf), abs(ysup)});
            const ll maxi = (j == 0) ? max({abs(yinf), abs(xinf), abs(xsup)}) : (j == 1) ? max({abs(xinf), abs(yinf), abs(ysup)}) : (j == 2) ? max({abs(ysup), abs(xinf), abs(xsup)}) : max({abs(xsup), abs(yinf), abs(ysup)});
            if (upper_bound(d.begin(), d.end(), maxi) - lower_bound(d.begin(), d.end(), mini) > 0) {
                cout << 2 << endl;
                return 0;
            }
        }
    }
    cout << -1 << endl;


    return 0;
}