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

    bd = dist[:]
    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]

    st = []
    used = [False] * n
    for i in range(n):
        if bd[i] != dist[i]:
            dist[i] = None
            st.append(i)
            used[i] = True
    E = [[] for _ in range(n)]
    for u, v, d in edges:
        E[u].append(v)

    while st:
        v = st.pop()
        for u in E[v]:
            if not used[u]:
                used[u] = True
                st.append(u)
                dist[u] = None

    return dist


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)[-1]
if ans is None:
    print("inf")
else:
    print(-ans)