N, T = map(int, input().split())
LEN = 2 * 10**5 + 2
c = [0] * LEN
for _ in range(N):
    _l, _r, _p = map(int, input().split())
    c[_l] += _p
    c[_r] -= _p
for i in range(1, LEN):
    if c[i] == 0:
        c[i] = c[i - 1]
    elif c[i] > 0:
        c[i] = max(c[i], c[i - 1])
    elif c[i - 1] + c[i] != 0:
        c[i] = c[i - 1]
p = [0] * LEN
i = 0
ans = 0
while i < LEN:
    if c[i] != 0:
        p[i + T] = c[i]
        i += 1
        break
    i += 1
while i < LEN:
    if p[i - 1] > p[i]:
        p[i] = p[i - 1]
    if c[i] > 0:
        if i + T >= LEN:
            ans = max(ans, c[i] + p[i])
        elif c[i] + p[i] > p[i + T]:
            p[i + T] = c[i] + p[i]
    i += 1

print(max(p[-1], ans))