import sys, math
sys.setrecursionlimit(10**8)
sys.set_int_max_str_digits(0)
INF = 1e18
MOD = 998244353
from bisect import bisect_left, bisect_right
from collections import deque, defaultdict, Counter
from itertools import product, combinations, permutations, groupby, accumulate
from heapq import heapify, heappop, heappush
def I():   return sys.stdin.readline().rstrip()
def II():  return int(sys.stdin.readline().rstrip())
def IS():  return sys.stdin.readline().rstrip().split()
def MII(): return map(int, sys.stdin.readline().rstrip().split())
def LI():  return list(sys.stdin.readline().rstrip())
def TII(): return tuple(map(int, sys.stdin.readline().rstrip().split()))
def LII(): return list(map(int, sys.stdin.readline().rstrip().split()))
def LSI(): return list(map(str, sys.stdin.readline().rstrip().split()))
def GMI(): return list(map(lambda x: int(x) - 1, sys.stdin.readline().rstrip().split()))
def kiriage(a, b): return (a+b-1)//b
def chmax(DP,i,v):
    if DP[i] < v: DP[i] = v
def chmin(DP,i,v):
    if DP[i] > v: DP[i] = v

N, T = MII()
data = []

in_event = defaultdict(list)
out_event = defaultdict(list)
for i in range(N):
    l, r, p = MII()
    data.append((l, r, p))
    in_event[l].append(i)
    out_event[r].append(i)

que = []
limit = 2*10**5
DP = [0]*(2*limit + 10)

for i in range(0, limit + 1):

    for idx in in_event[i]:
        heappush(que, (-data[idx][2], idx))
    
    while que and data[que[0][1]][1] < i:
        heappop(que)

    if que:
        score, idx = que[0]
        chmax(DP, i + T, DP[i] - score)

ans = max(DP)
print(ans)