from bisect import bisect_left
n, m = map(int, input().split())
ans = 0
l = list(map(int, input().split()))
ans = 0
for _ in range(m):
    f, b, w = map(int, input().split())
    i = bisect_left(l, f)
    if i < n:
        b = max(b, w - (l[i] - f))
    if i > 0:
        b = max(b, w - (f - l[i - 1]))
    ans += b
print(ans)