#MMA Contest 018 G

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

#DP[i]: ダンジョンiに到達したときの満足度の最大値
DP = [- 10 ** 18] * N
DP[0] = A[0]

#M回のBellman-Ford
for _ in range(M):
    for i in range(N):
        for j, c in G[i]:
            if DP[j] < DP[i] + c:
                DP[j] = min(DP[i] + c, 10 ** 18)

#もう1回Bellman-Ford  正回路があればinfに変更
for i in range(N):
    for j, c in G[i]:
        if DP[j] < DP[i] + c:
            DP[j] = 10 ** 18

#M回Bellman-Ford
for _ in range(M):
    for i in range(N):
        if DP[i] != 10 ** 18:
            continue
        for j, c in G[i]:
            if DP[j] < DP[i] + c:
                DP[j] = 10 ** 18

#答えを出力
print(DP[-1] if DP[-1] < 10 ** 18 else 'inf')