def bellmanFord(n, edges, s, inf=1 << 60):
    """
    edges = [(from1, to1, cost1), (from2, to2, cost2), ...)]
    """
    dist = [inf] * n
    dist[s] = 0

    for _ in range(n):
        update = False
        for u, v, d in edges:
            if dist[u] != inf and dist[v] > dist[u] + d:
                dist[v] = dist[u] + d
                update = True

        if not update:
            return -dist[-1]

    bd = dist[-1]
    for _ in range(n):
        update = False
        for u, v, d in edges:
            if dist[u] != inf and dist[v] > dist[u] + d:
                dist[v] = dist[u] + d
                update = True

        if not update:
            return -dist[-1]

    if bd != dist[-1]:
        return "inf"
    return -dist[-1]


n, m = map(int, input().split())
A = list(map(int, input().split()))
edges = []
for i, a in enumerate(A):
    edges.append((2 * i, 2 * i + 1, -a))
for _ in range(m):
    a, b, c = map(int, input().split())
    a -= 1
    b -= 1
    edges.append((2 * a + 1, 2 * b, c))

ans = bellmanFord(2 * n, edges, 0)
print(ans)