n, m = map(int, input().split())
a = list(map(int, input().split()))
g = [[] for _ in range(2 * n)]
g_inv = [[] for _ in range(2 * n)]
for i in range(n):
	g[i].append((i + n, -a[i]))
	g_inv[i + n].append(i)

for _ in range(m):
	a, b, c = map(int, input().split())
	a -= 1
	b -= 1
	g[a + n].append((b, c))
	g_inv[b].append(a + n)

reachable = [False] * (2 * n)
reachable[-1] = True
stack = [2 * n - 1]
while stack:
	u = stack.pop()
	for v in g_inv[u]:
		if not reachable[v]:
			reachable[v] = True
			stack.append(v)

INF = 10 ** 18
dist = [INF] * (2 * n)
dist[0] = 0

for _ in range(2 * n - 1):
	for u in range(2 * n):
		for v, w in g[u]:
			dist[v] = min(dist[v], dist[u] + w)

for u in range(2 * n):
	for v, w in g[u]:
		if reachable[v] and dist[v] > dist[u] + w:
			print("inf")
			exit()

print(-dist[-1])