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

partial class Solver {
    struct Edge {
        public int To { get; set; }
        public int Cost { get; set; }
    }

    public void Run() {
        int N = ni(), M = ni(), K = ni();
        var adj = Enumerable.Range(0, N).Select(_ => new List<Edge>()).ToArray();
        for (int i = 0; i < M; i++) {
            var a = ni();
            var b = ni();
            var c = ni();
            a--; b--;
            adj[a].Add(new Edge { To = b, Cost = c });
            adj[b].Add(new Edge { To = a, Cost = c });
        }
        var d = ni(K);

        var dp = new bool[K + 1, N];
        for (int i = 0; i < N; i++) {
            dp[0, i] = true;
        }
        for (int i = 0; i < K; i++) {
            for (int j = 0; j < N; j++) {
                if (!dp[i, j]) continue;
                foreach (var edge in adj[j]) {
                    if (edge.Cost == d[i]) {
                        dp[i + 1, edge.To] = true;
                    }
                }
            }
        }
        var ans = Enumerable.Range(0, N).Where(i => dp[K, i]).Select(i => i + 1).ToArray();
        cout.WriteLine(ans.Length);
        cout.WriteLine(String.Join(" ", ans));
    }
}

// PREWRITEN CODE BEGINS FROM HERE
partial class Solver : Scanner {
    public static void Main(string[] args) {
        new Solver(Console.In, Console.Out).Run();
    }

    TextReader cin;
    TextWriter cout;

    public Solver(TextReader reader, TextWriter writer)
        : base(reader) {
        this.cin = reader;
        this.cout = writer;
    }
    public Solver(string input, TextWriter writer)
        : this(new StringReader(input), writer) {
    }

    public int ni() { return NextInt(); }
    public int[] ni(int n) { return NextIntArray(n); }
    public long nl() { return NextLong(); }
    public long[] nl(int n) { return NextLongArray(n); }
    public string ns() { return Next(); }
}

public class Scanner {
    private TextReader Reader;
    private Queue<String> TokenQueue = new Queue<string>();
    private CultureInfo ci = CultureInfo.InvariantCulture;

    public Scanner()
        : this(Console.In) {
    }

    public Scanner(TextReader reader) {
        this.Reader = reader;
    }

    public int NextInt() { return Int32.Parse(Next(), ci); }
    public long NextLong() { return Int64.Parse(Next(), ci); }
    public double NextDouble() { return double.Parse(Next(), ci); }
    public string[] NextArray(int size) {
        var array = new string[size];
        for (int i = 0; i < size; i++) array[i] = Next();
        return array;
    }
    public int[] NextIntArray(int size) {
        var array = new int[size];
        for (int i = 0; i < size; i++) array[i] = NextInt();
        return array;
    }

    public long[] NextLongArray(int size) {
        var array = new long[size];
        for (int i = 0; i < size; i++) array[i] = NextLong();
        return array;
    }

    public String Next() {
        if (TokenQueue.Count == 0) {
            if (!StockTokens()) throw new InvalidOperationException();
        }
        return TokenQueue.Dequeue();
    }

    public bool HasNext() {
        if (TokenQueue.Count > 0)
            return true;
        return StockTokens();
    }

    private bool StockTokens() {
        while (true) {
            var line = Reader.ReadLine();
            if (line == null) return false;
            var tokens = line.Trim().Split(" ".ToCharArray(), StringSplitOptions.RemoveEmptyEntries);
            if (tokens.Length == 0) continue;
            foreach (var token in tokens)
                TokenQueue.Enqueue(token);
            return true;
        }
    }
}