from heapq import heapify, heappop, heappush
from collections import defaultdict


def main():
    INF = 10 ** 18
    n, m = map(int, input().split())
    g = defaultdict(list)
    for _ in range(m):
        a, b, c = map(int, input().split())
        a -= 1
        b -= 1
        g[a].append([b, c])
        g[b].append([a, c])
    t = list(map(int, input().split()))

    # ダイクストラ
    dist = [[INF] * 501 for _ in range(n)]
    dist[0][0] = 0
    q = [(0, 0, 0)]  # (今の時間, 今いる頂点，おむすびを食べた時間)
    while q:
        cur_t, cur_v, eat_t = heappop(q)
        if dist[cur_v][eat_t] < cur_t:
            continue
        cur_t += t[cur_v]
        eat_t = min(eat_t + t[cur_v], 500)
        for v, cost in g[cur_v]:
            if dist[v][eat_t] > cur_t + cost // eat_t:
                dist[v][eat_t] = cur_t + cost // eat_t
                heappush(q, (cur_t + cost // eat_t, v, eat_t))
    print(min(dist[- 1]))


if __name__ == "__main__":
    main()