import sys

# sys.setrecursionlimit(200005)
# sys.set_int_max_str_digits(200005)
int1 = lambda x: int(x)-1
pDB = lambda *x: print(*x, end="\n", file=sys.stderr)
p2D = lambda x: print(*x, sep="\n", end="\n\n", file=sys.stderr)
def II(): return int(sys.stdin.readline())
def LI(): return list(map(int, sys.stdin.readline().split()))
def LLI(rows_number): return [LI() for _ in range(rows_number)]
def LI1(): return list(map(int1, sys.stdin.readline().split()))
def LLI1(rows_number): return [LI1() for _ in range(rows_number)]
def SI(): return sys.stdin.readline().rstrip()

dij = [(0, 1), (-1, 0), (0, -1), (1, 0)]
# dij = [(0, 1), (-1, 0), (0, -1), (1, 0), (1, 1), (1, -1), (-1, 1), (-1, -1)]
# inf = -1-(-1 << 31)
inf = -1-(-1 << 62)

# md = 10**9+7
md = 998244353

from heapq import *

lim=200001
n,t=LI()
lp=[]
rp=[]
for _ in range(n):
    l,r,p=LI()
    lp.append((l,p))
    rp.append((r,p))
lp.sort(key=lambda x:-x[0])
rp.sort(key=lambda x:-x[0])

dp=[0]*lim
hp=[0]
rem=[]
for i in range(lim):
    while lp and lp[-1][0]==i:
        _,p=lp.pop()
        heappush(hp,-p)
    while rem and hp[0]==rem[0]:
        heappop(hp)
        heappop(rem)
    dp[i]=max(dp[i-1],-hp[0])
    if i>=t:dp[i]=max(dp[i],dp[i-t]-hp[0])
    while rp and rp[-1][0]==i:
        _,p=rp.pop()
        heappush(rem,-p)
print(dp[-1])