import java.util.ArrayList; import java.util.Arrays; import java.util.Scanner; public class Main92 { public static void main(String[] args) { Main92 p = new Main92(); } public Main92() { Scanner sc = new Scanner(System.in); int n = sc.nextInt(); int m = sc.nextInt(); int k = sc.nextInt(); d = new int[k]; ArrayList<ArrayList<Edge>> city = new ArrayList<ArrayList<Edge>>(); for(int i=0;i<n;i++){ city.add(new ArrayList<Edge>()); } for(int i=0;i<m;i++){ int a = sc.nextInt()-1; int b = sc.nextInt()-1; int c = sc.nextInt(); city.get(a).add(new Edge(b, c)); city.get(b).add(new Edge(a, c)); } for(int i=0;i<k;i++) d[i] = sc.nextInt(); solve(n,m,k,city); } private boolean[] isOk; private int[] d; private int[][] memo; public void solve(int n, int m, int k, ArrayList<ArrayList<Edge>> city) { isOk = new boolean[city.size()]; memo = new int[n][k]; for(int i=0;i<n;i++) dfs(i, 0, city); int c = 0; for(int i=0;i<isOk.length;i++) if(isOk[i]) c++; System.out.println(c); for(int i=0;i<isOk.length;i++){ if(isOk[i]){ c--; System.out.print((i+1) + "" + (c>0 ? ' ' : '\n')); } } } private void dfs(int curc, int curk, ArrayList<ArrayList<Edge>> city) { // System.out.println(curc+" "+curk); if(curk==d.length){ isOk[curc] = true; return; } if(memo[curc][curk]==1) return; for(int i=0;i<city.get(curc).size();i++){ if(city.get(curc).get(i).c==d[curk]) dfs(city.get(curc).get(i).b, curk+1, city); memo[curc][curk] = 1; } } private class Edge{ int b; int c; public Edge(int b, int c) { this.b = b; this.c = c; } } }