from collections import namedtuple

Edge = namedtuple("Edge", ["from_", "to", "cost"])

def bellman_ford(st, dist, edges):
    N = len(dist)
    for i in range(N):
        dist[i] = -float('inf')
    dist[st] = 0
    for _ in range(N):
        update = False
        for e in edges:
            if dist[e.to] < dist[e.from_] + e.cost:
                dist[e.to] = dist[e.from_] + e.cost
                update = True
        if not update:
            return True
    return False

if __name__ == "__main__":
    N, M = map(int, input().split())
    A = list(map(int, input().split()))

    edges = []
    for _ in range(M):
        a, b, c = map(int, input().split())
        a -= 1
        b -= 1
        edges.append(Edge(a + N, b, -c))
    for i in range(N):
        edges.append(Edge(i, i + N, A[i]))

    dist = [-float('inf')] * (2 * N)
    f = bellman_ford(0, dist, edges)
    if f:
        print(dist[2 * N - 1])
    else:
        print("inf")