# 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()))


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, c - A[b]))

MINF = 10**18
dist = [MINF] * N
dist[0] = -A[0]
exist_negative_cycle = False
for i in range(N):
    update = False
    for u in range(N):
        if dist[u] == MINF:
            continue
        for v, c in G[u]:
            if dist[v] > dist[u] + c:
                dist[v] = dist[u] + c
                update = True

    if not update:
        break

    if i == N - 1 and update:
        exist_negative_cycle = True

for i in range(N):
    for u in range(N):
        if dist[u] == MINF:
            continue
        for v, c in G[u]:
            threshold = dist[u] + c
            if threshold < dist[v]:
                dist[v] = -MINF

ans = -dist[N - 1]
print(ans if dist[N - 1] != -MINF else "inf")