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();
    static int[] NMi => ReadLine().Split().Select(c => int.Parse(c) - 1).ToArray();
    static int[][] NMap(int n) => Enumerable.Repeat(0, n).Select(_ => NMi).ToArray();

    public static void Main()
    {
        Solve();
    }
    static void Solve()
    {
        var c = NList;
        var (n, m) = (c[0], c[1]);
        var map = NMap(m);
        var k = NN;
        var a = new int[0];
        if (k > 0) a = NMi;

        var tree = new List<int>[n];
        for (var i = 0; i < n; ++i) tree[i] = new List<int>();
        foreach (var edge in map)
        {
            tree[edge[0]].Add(edge[1]);
            tree[edge[1]].Add(edge[0]);
        }
        var iwi = new bool[n];
        foreach (var ai in a) iwi[ai] = true;

        var INF = int.MaxValue / 2;
        var dp = Enumerable.Repeat(INF, n * 5).ToArray();
        dp[0] = 0;
        var q = new Queue<int>();
        q.Enqueue(0);
        while (q.Count > 0)
        {
            var cur = q.Dequeue();
            if (cur % n == n - 1)
            {
                WriteLine(dp[cur]);
                return;
            }
            var d = cur / n;
            foreach (var next in tree[cur % n])
            {
                var nnum = next;
                if (iwi[nnum % n]) nnum += (d + 1) * n;
                if (nnum >= dp.Length) continue;
                if (dp[nnum] <= dp[cur] + 1) continue;
                dp[nnum] = dp[cur] + 1;
                q.Enqueue(nnum);
            }
        }
        WriteLine(-1);
    }
}