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

MAX_INT = 10 ** 18

from collections import deque

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

    next_nodes = [[] for _ in range(N + 1)]
    for a, b, _ in new_edges:
        next_nodes[b].append(a)

    queue = deque()
    queue.append(N)
    passed = [False] * ( N + 1)
    passed[N] = True
    while len(queue) > 0:
        v = queue.popleft()
        for w in next_nodes[v]:
            if not passed[w]:
                passed[w] = True
                queue.append(w)
    
    for i in range(N + 1):
        if passed[i] and costs[i] == -MAX_INT:
            print("inf")
            return 
        
    print(-costs[N])









if __name__ == "__main__":
    main()