Baekjoon #17396

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

public class Main {
    public static void main(String[] args) {
        FastReader rd = new FastReader();
        int N = rd.nextInt();
        int M = rd.nextInt();

        int[] a = new int[N];
        for (int i = 0; i < N; i++) {
            a[i] = rd.nextInt();
        }

        List<Node> list[] = new ArrayList[N];
        for (int i = 0; i < N; i++) {
            list[i] = new ArrayList<>();
        }

        for (int i = 0; i < M; i++) {
            int n1 = rd.nextInt();
            int n2 = rd.nextInt();
            int dist = rd.nextInt();

            boolean check1 = check(n1, a);
            boolean check2 = check(n2, a);

            if (check1 && check2) {
                list[n1].add(new Node(n2, dist));
                list[n2].add(new Node(n1, dist));
            }
        }

        long[] dist = new long[N];
        long INF = (long) 3e11 + 4;
        Arrays.fill(dist, INF);
        dist[0] = 0;

        PriorityQueue<Node> pq = new PriorityQueue<>();
        pq.add(new Node(0, 0));
        while (!pq.isEmpty()) {
            Node curr = pq.poll();

            if (dist[curr.id] < curr.dist) continue;

            for (Node next : list[curr.id]) {
                if (dist[next.id] > curr.dist + next.dist) {
                    dist[next.id] = curr.dist + next.dist;
                    pq.add(new Node(next.id, dist[next.id]));
                }
            }
        }

        //		System.out.println(-1);
        long ans = dist[N - 1] == INF ? -1 : dist[N - 1];
        System.out.println(ans);
    }

    private static boolean check(int node, int[] a) {
        return node == a.length - 1 || a[node] == 0;
    }

    private static class Node implements Comparable<Node> {
        int id;
        long dist;


        Node(int id, long dist) {
            this.id = id;
            this.dist = dist;
        }

        @Override
        public int compareTo(Node o) {
            return Long.compare(this.dist, o.dist);
        }
    }

    static class FastReader {
        BufferedReader br;
        StringTokenizer st;

        public FastReader() {
            br = new BufferedReader(new InputStreamReader(System.in));
        }

        String next() {
            while (st == null || !st.hasMoreElements()) {
                try {
                    st = new StringTokenizer(br.readLine());
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            return st.nextToken();
        }

        int nextInt() {
            return Integer.parseInt(next());
        }

        long nextLong() {
            return Long.parseLong(next());
        }

        double nextDouble() {
            return Double.parseDouble(next());
        }

        String nextLine() {
            String str = "";
            try {
                str = br.readLine();
            } catch (IOException e) {
                e.printStackTrace();
            }
            return str;
        }
    }
}