class LazySegTree_RAQ:
    def __init__(self,init_val,segfunc,ide_ele):
        n = len(init_val)
        self.segfunc = segfunc
        self.ide_ele = ide_ele
        self.num = 1<<(n-1).bit_length()
        self.tree = [ide_ele]*2*self.num
        self.lazy = [0]*2*self.num
        for i in range(n):
            self.tree[self.num+i] = init_val[i]
        for i in range(self.num-1,0,-1):
            self.tree[i] = self.segfunc(self.tree[2*i], self.tree[2*i+1])
    def gindex(self,l,r):
        l += self.num
        r += self.num
        lm = l>>(l&-l).bit_length()
        rm = r>>(r&-r).bit_length()
        while r>l:
            if l<=lm:
                yield l
            if r<=rm:
                yield r
            r >>= 1
            l >>= 1
        while l:
            yield l
            l >>= 1
    def propagates(self,*ids):
        for i in reversed(ids):
            v = self.lazy[i]
            if v==0:
                continue
            self.lazy[i] = 0
            self.lazy[2*i] += v
            self.lazy[2*i+1] += v
            self.tree[2*i] += v
            self.tree[2*i+1] += v
    def add(self,l,r,x):
        ids = self.gindex(l,r)
        l += self.num
        r += self.num
        while l<r:
            if l&1:
                self.lazy[l] += x
                self.tree[l] += x
                l += 1
            if r&1:
                self.lazy[r-1] += x
                self.tree[r-1] += x
            r >>= 1
            l >>= 1
        for i in ids:
            self.tree[i] = self.segfunc(self.tree[2*i], self.tree[2*i+1]) + self.lazy[i]
    def query(self,l,r):
        self.propagates(*self.gindex(l,r))
        res = self.ide_ele
        l += self.num
        r += self.num
        while l<r:
            if l&1:
                res = self.segfunc(res,self.tree[l])
                l += 1
            if r&1:
                res = self.segfunc(res,self.tree[r-1])
            l >>= 1
            r >>= 1
        return res


n,A=map(int,input().split())
p=[tuple(map(int,input().split())) for i in range(n)]
xz=[]
yz=[]
for x,y,v in p:
  xz+=[x-A+1,x+1]
  yz+=[y,y+A]
xz=sorted(set(xz))
xd={v:i for i,v in enumerate(xz)}
yz=sorted(set(yz))
yd={v:i for i,v in enumerate(yz)}
yq=[[] for i in range(len(yz))]
for x,y,v in p:
  yq[yd[y]]+=[(xd[x-A+1],xd[x+1],v)]
  yq[yd[y+A]]+=[(xd[x-A+1],xd[x+1],-v)]
st=LazySegTree_RAQ([0]*len(xz),max,0)
ans=0
for i in range(len(yz)):
  for l,r,v in yq[i]:
    st.add(l,r,v)
  ans=max(ans,st.query(0,len(xz)))
print(ans)