from bisect import bisect_left, bisect_right

def segfunc(x,y):
    return max(x, y)
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()
        ans = []
        while r>l:
            if l<=lm:
                ans.append(l)
            if r<=rm:
                ans.append(r)
            r >>= 1
            l >>= 1
        while l:
            ans.append(l)
            l >>= 1
        return ans
    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 = sorted([list(map(int, input().split())) for _ in range(N)], key=lambda x:x[0])

INF = 1<<60

def compress(A):
    S = sorted(set(A))
    D = dict()
    for i in range(len(S)):
        D[S[i]] = i
    return D, S

def func(B):
    X = []
    Y = []
    for x, y, v in P:
        X.append(x+B)
        X.append(x)
        X.append(x+B+1)
        X.append(x-1)
        Y.append(y)
        Y.append(y-A)
        Y.append(y-(A-1))
        Y.append(y+1)
        Y.append(y-A-1)
        Y.append(y-(A-1)-1)
    X = sorted(set(X))
    D, S = compress(Y)
    L1 = []
    L2 = []
    for i in range(len(S)):
        L1.append(bisect_left(S, S[i]-A))
        L2.append(bisect_left(S, S[i]-(A-1)))
    seg1 = LazySegTree_RAQ([0]*len(D), segfunc, -INF)
    seg2 = LazySegTree_RAQ([0]*len(D), segfunc, -INF)
    idxR = 0
    idxL = 0
    ans = 0
    for x in X:
        while idxR < N and P[idxR][0] <= x:
            _, y, v = P[idxR]
            seg1.add(L1[D[y]], D[y]+1, v)
            seg2.add(L2[D[y]], D[y]+1, v)
            idxR += 1
        while idxL < N and P[idxL][0] < x-B:
            _, y, v = P[idxL]
            seg1.add(L1[D[y]], D[y]+1, -v)
            seg2.add(L2[D[y]], D[y]+1, -v)
            idxL += 1
        ans = max(ans, seg1.query(0, len(D)), seg2.query(0, len(D)))
    return ans

print(max(func(A), func(A-1), 0))