## https://yukicoder.me/problems/no/2712

MAX_INT = 10 ** 18

def 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())
        edges.append((a, b, c))

    new_edges = []
    for a, b, c in edges:
        new_edges.append((a, b, -A[b - 1] + c))
    
    new_edges.append((0, 1, -A[0]))

    # ベルマンフォード
    costs = [MAX_INT] * (N + 1)
    costs[0] = 0

    for i in range(N + 1):

        for a, b, c in new_edges:
            new_cost = costs[a] + c
            if costs[b] > new_cost:
                if i >= N:
                    costs[b] = -MAX_INT
                else:
                    costs[b] = new_cost
    
    if costs[N] == -MAX_INT:
        print("inf")
    else:
        print(-costs[N])







if __name__ == "__main__":
    main()