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

class Program
{
    static string InputPattern = "InputX";

    static List<string> GetInputList()
    {
        var WillReturn = new List<string>();

        if (InputPattern == "Input1") {
            WillReturn.Add("13 13");
            WillReturn.Add("1 2");
            WillReturn.Add("2 3");
            WillReturn.Add("3 4");
            WillReturn.Add("4 5");
            WillReturn.Add("5 6");
            WillReturn.Add("6 13");
            WillReturn.Add("1 7");
            WillReturn.Add("7 8");
            WillReturn.Add("8 9");
            WillReturn.Add("9 10");
            WillReturn.Add("9 12");
            WillReturn.Add("10 11");
            WillReturn.Add("11 13");
            WillReturn.Add("10");
            WillReturn.Add("2 3 4 5 6 7 8 9 10 11");
            //8
        }
        else if (InputPattern == "Input2") {
            WillReturn.Add("7 6");
            WillReturn.Add("1 2");
            WillReturn.Add("2 3");
            WillReturn.Add("3 4");
            WillReturn.Add("4 5");
            WillReturn.Add("5 6");
            WillReturn.Add("6 7");
            WillReturn.Add("5");
            WillReturn.Add("2 3 4 5 6");
            //-1
        }
        else if (InputPattern == "Input3") {
            WillReturn.Add("3 2");
            WillReturn.Add("1 2");
            WillReturn.Add("2 3");
            WillReturn.Add("0");
            //2
        }
        else {
            string wkStr;
            while ((wkStr = Console.ReadLine()) != null) WillReturn.Add(wkStr);
        }
        return WillReturn;
    }

    static long[] GetSplitArr(string pStr)
    {
        return (pStr == "" ? new string[0] : pStr.Split(' ')).Select(pX => long.Parse(pX)).ToArray();
    }

    static HashSet<long> mKSet = new HashSet<long>();

    // 隣接リスト
    static Dictionary<long, List<long>> mToNodeListDict = new Dictionary<long, List<long>>();

    static long mN;

    static void Main()
    {
        List<string> InputList = GetInputList();

        long[] wkArr = { };
        Action<string> SplitAct = (pStr) => wkArr = GetSplitArr(pStr);

        SplitAct(InputList[0]);
        mN=wkArr[0];
        long M = wkArr[1];

        foreach (string EachStr in InputList.Skip(1).Take((int)M)) {
            SplitAct(EachStr);
            long FromNode = wkArr[0];
            long ToNode = wkArr[1];

            if (mToNodeListDict.ContainsKey(FromNode) == false) {
                mToNodeListDict[FromNode] = new List<long>();
            }
            if (mToNodeListDict.ContainsKey(ToNode) == false) {
                mToNodeListDict[ToNode] = new List<long>();
            }
            mToNodeListDict[FromNode].Add(ToNode);
            mToNodeListDict[ToNode].Add(FromNode);
        }

        long K = long.Parse(InputList[(int)M + 1]);
        if (K >= 1) {
            SplitAct(InputList.Last());
            mKSet.UnionWith(wkArr);
        }

        var Que = new Queue<JyoutaiDef>();
        JyoutaiDef WillEnqueue;
        WillEnqueue.CurrNode = 1;
        WillEnqueue.IwaiCnt = 0;
        WillEnqueue.Cost = 0;
        Que.Enqueue(WillEnqueue);

        long Answer = long.MaxValue;
        bool HasAnswer = false;

        // 最小コスト[ハッシュ]
        var EadakiriDict = new Dictionary<long, long>();
        while (Que.Count > 0) {
            JyoutaiDef Dequeued=Que.Dequeue();

            // クリア判定
            if (Dequeued.CurrNode == mN) {
                HasAnswer = true;
                Answer = Math.Min(Answer, Dequeued.Cost);
                continue;
            }

            if (HasAnswer) {
                if (Answer <= Dequeued.Cost) continue;
            }

            foreach (long EachToNode in mToNodeListDict[Dequeued.CurrNode]) {
                WillEnqueue.CurrNode = EachToNode;
                WillEnqueue.IwaiCnt = Dequeued.IwaiCnt;
                if (mKSet.Contains(EachToNode)) {
                    WillEnqueue.IwaiCnt++;
                }
                else {
                    WillEnqueue.IwaiCnt = 0;
                }
                if (WillEnqueue.IwaiCnt == 5) continue;

                WillEnqueue.Cost = Dequeued.Cost + 1;

                long Hash = GetHash(EachToNode, WillEnqueue.IwaiCnt);
                if (EadakiriDict.ContainsKey(Hash)) {
                    if (EadakiriDict[Hash] <= WillEnqueue.Cost) {
                        continue;
                    }
                }
                EadakiriDict[Hash] = WillEnqueue.Cost;

                Que.Enqueue(WillEnqueue);
            }
        }
        if (HasAnswer) {
            Console.WriteLine(Answer);
        }
        else {
            Console.WriteLine(-1);
        }
    }

    static long GetHash(long pNode, long pIwaiCnt)
    {
        return pNode * 10 + pIwaiCnt;
    }

    struct JyoutaiDef
    {
        internal long CurrNode;
        internal long IwaiCnt;
        internal long Cost;
    }
}