// Author: Adrian Kuegel
// Date: July 10th, 2009
// Complexity: O(n * h)

import java.util.*;
import java.io.*;

class Edge {
	private int dest, c;
	public Edge(int destination, int cost) {
		dest = destination;
		c = cost;
	}
	public int getDestination() {
		return dest;
	}
	public int getCost() {
		return c;
	}
}

public class hotel {
	public static void main(String [] args) throws Exception {
		BufferedReader br = new BufferedReader(new FileReader("hotel.in"));
		int n;
		boolean [] has_hotel = new boolean[10000];
		int [] d = new int[10000];
		int [] Q = new int[101];
		ArrayList [] r = new ArrayList[601];
		for (int i=0; i<601; ++i)
			r[i] = new ArrayList();
		ArrayList [] adj = new ArrayList[10000];
		for (int i=0; i<10000; ++i)
			adj[i] = new ArrayList();
		while((n = Integer.parseInt(br.readLine())) != 0) {
			for (int i=0; i<n; ++i) {
				has_hotel[i] = false;
				adj[i].clear();
			}
			has_hotel[n-1] = true;
			StringTokenizer strTok = new StringTokenizer(br.readLine());
			int h = Integer.parseInt(strTok.nextToken());
			for (int i=0; i<h; ++i) {
				int a = Integer.parseInt(strTok.nextToken());
				has_hotel[a-1] = true;
			}
			int m = Integer.parseInt(br.readLine());
			while(m-- > 0) {
				strTok = new StringTokenizer(br.readLine());
				int a = Integer.parseInt(strTok.nextToken()) - 1;
				int b = Integer.parseInt(strTok.nextToken()) - 1;
				int dist = Integer.parseInt(strTok.nextToken());
				adj[a].add(new Edge(b, dist));
				adj[b].add(new Edge(a, dist));
			}
			Q[0] = 0;
			int l = 1, res = -1;
			while(l > 0 && has_hotel[n-1]) {
				++res;
				for (int i=0; i<=600; ++i)
					r[i].clear();
				for (int i=0; i<n; ++i)
					d[i] = Integer.MAX_VALUE;
				for (int i=0; i<l; ++i) {
					d[Q[i]] = 0;
					r[0].add(Q[i]);
				}
				l = 0;
				// modified dijkstra which uses the fact that we are only interested in distances <= 600
				for (int i=0; i<=600; ++i) {
					for (Iterator it = r[i].iterator(); it.hasNext();) {
						int c = (Integer)it.next();
						if (d[c] < i)
							continue;
						if (has_hotel[c]) {
							has_hotel[c] = false;
							Q[l++] = c;
						}
						for (Iterator it2 = adj[c].iterator(); it2.hasNext(); ) {
							Edge e = (Edge)it2.next();
							int ndist = e.getCost() + i;
							if (ndist <= 600 && ndist < d[e.getDestination()]) {
								d[e.getDestination()] = ndist;
								r[ndist].add(e.getDestination());
							}
						}
					}
				}
			}
			System.out.println(has_hotel[n-1]? -1 : res);
		}
	}
}