import std.stdio, std.string, std.conv, std.algorithm, std.numeric;
import std.range, std.array, std.math, std.typecons, std.container, core.bitop;


void main() {
    int n;
    scan(n);

    auto d = readln.split.to!(int[]);
    int x, y;
    scan(x, y);

    long L = abs(x) + abs(y);

    if (L == 0) {
        writeln(0);
        return;
    }

    foreach (i ; 0 .. n) {
        if (d[i] == L) {
            writeln(1);
            return;
        }
    }

    d.sort();

    auto ev = new int[](0);
    auto od = new int[](0);

    foreach (i ; 0 .. n) {
        if (d[i] & 1) od ~= d[i];
        else ev ~= d[i];
    }

    debug {
        writeln(ev);
        writeln(od);
    }

    foreach (i ; 0 .. n) {
        long ue = L + d[i], sita;

        if (d[i] <= L) {
            sita = L - d[i];
        }
        else {
            sita = d[i] - L;
        }

        if (ue & 1) {
            auto seg = od.assumeSorted.lowerBound(ue + 1);
            auto segs = seg.assumeSorted.upperBound(sita -1);
            if (!segs.empty) {
                writeln(2);
                return;
            }
        }
        else {
            auto seg = ev.assumeSorted.lowerBound(ue+1);
            auto segs = seg.assumeSorted.upperBound(sita-1);
            if (!segs.empty) {
                writeln(2);
                return;
            }
        }
    }

    writeln(-1);
}


void scan(T...)(ref T args) {
    string[] line = readln.split;
    foreach (ref arg; args) {
        arg = line.front.to!(typeof(arg));
        line.popFront();
    }
    assert(line.empty);
}


void fillAll(R, T)(ref R arr, T value) {
    static if (is(typeof(arr[] = value))) {
        arr[] = value;
    }
    else {
        foreach (ref e; arr) {
            fillAll(e, value);
        }
    }
}