using System;
using static System.Console;
using System.Linq;
using System.Collections.Generic;

class Program
{
    static int NN => int.Parse(ReadLine());
    static int[] NList => ReadLine().Split().Select(int.Parse).ToArray();
    public static void Main()
    {
        Solve();
    }
    static void Solve()
    {
        var n = NN;
        var d = NList;
        var c = NList;
        var x = (long)Math.Abs(c[0]) + Math.Abs(c[1]);
        var emax = -1;
        var omax = -1;
        if (x == 0)
        {
            WriteLine(0);
            return;
        }
        foreach (var di in d)
        {
            if (x == di)
            {
                WriteLine(1);
                return;
            }
            if (di % 2 == 0) emax = Math.Max(emax, di);
            else omax = Math.Max(omax, di);
        }
        var e2max = -1;
        var o2max = -1;
        if (emax > 0) e2max = Math.Max(e2max, emax * 2);
        if (omax > 0) e2max = Math.Max(e2max, omax * 2);
        if (emax > 0 && omax > 0) o2max = emax + omax;
        if (x % 2 == 0) WriteLine(x <= e2max ? 2 : -1);
        else WriteLine(x <= o2max ? 2 : -1);
    }
}