# 標準入力された値を整数に変換する
def INT():
    return int(input())


# 標準入力された複数の値を整数に変換する
def MI():
    return map(int, input().split())


# 標準入力された複数の値を整数のリストに変換する
def LI():
    return list(map(int, input().split()))


import heapq


def dijkstra(n, G, start=0):
    MINF = -(10**18)
    dist = [MINF] * n
    dist[start] = A[start]
    pq = []
    heapq.heappush(pq, (0, start))
    visited = [False] * n

    while pq:
        now = heapq.heappop(pq)[1]
        visited[now] = True
        for nxt, cost in G[now]:
            if dist[nxt] < dist[now] + cost and not visited[nxt]:
                dist[nxt] = dist[now] + cost
                heapq.heappush(pq, (dist[now] + cost, nxt))

    return dist


N, M = MI()
A = LI()
G = [[] for i in range(N)]
for _ in range(M):
    a, b, c = MI()
    a -= 1
    b -= 1
    G[a].append((b, A[b] - c))

dist = []
for i in range(N):
    d = dijkstra(N, G, i)
    dist.append(d)

for i in range(N):
    for j in range(N):
        if i == j:
            continue
        if dist[0][i] >= 0 and dist[i][j] > 0 and dist[j][i] > 0:
            print("inf")
            exit()

print(dist[0][N - 1])