import typing


class DSU:
    '''
    Implement (union by size) + (path halving)

    Reference:
    Zvi Galil and Giuseppe F. Italiano,
    Data structures and algorithms for disjoint set union problems
    '''

    def __init__(self, n: int = 0) -> None:
        self._n = n
        self.parent_or_size = [-1] * n

    def merge(self, a: int, b: int) -> int:
        assert 0 <= a < self._n
        assert 0 <= b < self._n

        x = self.leader(a)
        y = self.leader(b)

        if x == y:
            return x

        if -self.parent_or_size[x] < -self.parent_or_size[y]:
            x, y = y, x

        self.parent_or_size[x] += self.parent_or_size[y]
        self.parent_or_size[y] = x

        return x

    def same(self, a: int, b: int) -> bool:
        assert 0 <= a < self._n
        assert 0 <= b < self._n

        return self.leader(a) == self.leader(b)

    def leader(self, a: int) -> int:
        assert 0 <= a < self._n

        parent = self.parent_or_size[a]
        while parent >= 0:
            if self.parent_or_size[parent] < 0:
                return parent
            self.parent_or_size[a], a, parent = (
                self.parent_or_size[parent],
                self.parent_or_size[parent],
                self.parent_or_size[self.parent_or_size[parent]]
            )

        return a

    def size(self, a: int) -> int:
        assert 0 <= a < self._n

        return -self.parent_or_size[self.leader(a)]

    def groups(self) -> typing.List[typing.List[int]]:
        leader_buf = [self.leader(i) for i in range(self._n)]

        result: typing.List[typing.List[int]] = [[] for _ in range(self._n)]
        for i in range(self._n):
            result[leader_buf[i]].append(i)

        return list(filter(lambda r: r, result))
from heapq import *
N, M = map(int, input().split())
A = list(map(int, input().split()))
g = []
uf = DSU(N)
for _ in range(M):
	a, b, c = map(int, input().split())
	a -= 1
	b -= 1
	g.append((a, b, c))
	uf.merge(a, b)
s = []
for i in range(N):
	if uf.same(0, i):
		s.append(i)
ok = set(s)
es = []
for i, j, c in g:
	if i in ok and j in ok:
		es.append((i, j, c))

inf = 10 ** 20

dist = [-inf] * N
dist[0] = 0
for i in range(N + 1):
	for u, v, c in es:
		if dist[u] != -inf and dist[v] < dist[u] + A[v] - c:
			dist[v] = dist[u] + A[v] - c
for u, v, c in es:
	if uf.same(0, u) and uf.same(N - 1, u) and dist[u] != -inf and dist[v] < dist[u] + A[v] - c:
		exit(print("inf"))
print(max(0, dist[N - 1] + A[0]) if dist[N - 1] > -inf else "inf")