uri1640

#include <bits/stdc++.h>

#define fi first
#define se second

using namespace std;

typedef pair<int, int> ii;
typedef vector<ii> vii;

int N, m, a, b, t, nh;
int h[10001];
vii G[10001];
int ans[10001];

void dfs(int n, int sz, int ht)
{

	ans[n] = min(ans[n], ht);
	for (int i = 0; i < G[n].size(); i++) {
		if (ht < ans[G[n][i].fi])
		{
		if (G[n][i].se + sz <= 600)
			dfs(G[n][i].fi, G[n][i].se + sz, ht); //nao descanso
		if (h[n] == 1)
			dfs(G[n][i].fi, G[n][i].se, ht + 1); //descanso
		}
		else if (ht == ans[G[n][i].fi])
		{

		}
	}

}


int main()
{
	while (cin >> N && N)
	{
		for (int i = 0; i < N; i++) {
			G[i+1].clear();
			ans[i+1] = 1 << 30;
		}

		cin >> nh;
		memset(h, 0, sizeof h);
		for (int i = 0; i < nh; i++) {
			cin >> t; h[t] = 1;
		}

		cin >> m;
		for (int i = 0; i < m; i++) {
			cin >> a >> b >> t;
			G[a].push_back(ii(b, t));
			G[b].push_back(ii(a, t));
		}

		dfs(1, 0, 0);
		cout << (ans[N] == (1 << 30) ? -1 : ans[N]) << endl;
	}

	return 0;
}