using System;
using System.Linq;
using System.Collections.Generic;
using System.Text;

public class Program
{
    public void Proc() {
        Reader.IsDebug = false;
        int itemCount = int.Parse(Reader.ReadLine());

        this.items = Reader.ReadLine().Split(' ').Select(a=>long.Parse(a)).OrderByDescending(a=>a).ToArray();

        this.range = Reader.ReadLine().Split(' ').Select(a=>Math.Abs(long.Parse(a))).Max();

        Dictionary<long, long> dic = new Dictionary<long, long>();

        long pos = range;
        dic.Add(pos, 0);
        Queue<long> que = new Queue<long>();
        que.Enqueue(pos);
        while(que.Count > 0) {
            pos = que.Dequeue();
            if(pos == 0) {
                break;
            }
            if(pos % items[0] == 0) {
                if((!dic.ContainsKey(0)) || dic[0] > pos / items[0]) {
                    dic[0] = pos / items[0] + dic[pos];
                    continue;
                }
            }
            long step = dic[pos];
            items.ToList().ForEach(a=>{
                long[] tmp = new long[]{a, a*-1};
                foreach(long item in tmp) {
                    long nextPos = pos + item;
                    if(pos >= 0 && nextPos >= 0 && nextPos > items[0] && nextPos > pos) {
                        continue;
                    }
                    if(pos <= 0 && nextPos <= 0 && nextPos < (items[0]*-1) && nextPos < pos) {
                        continue;
                    }
                    if(dic.ContainsKey(nextPos) && dic[nextPos] <= step + 1) {
                        continue;
                    }
                    dic[nextPos] = step + 1;
                    que.Enqueue(nextPos);
                }
            });
        }
        if(dic.ContainsKey(0)) {
            Console.WriteLine(dic[0]);
        } else {
            Console.WriteLine(-1);
        }
    }


    private long[] items;
    private long range;



    public class Reader {
        public static bool IsDebug = true;
        private static System.IO.StringReader SReader;
        private static string InitText = @"


3
3 4 5
12 12

";
        public static string ReadLine() {
            if(IsDebug) {
                if(SReader == null) {
                    SReader = new System.IO.StringReader(InitText.Trim());
                }
                return SReader.ReadLine();
            } else {
                return Console.ReadLine();
            }
        }
    }
    public static void Main(string[] args)
    {
        Program prg = new Program();
        prg.Proc();
    }
}