Buggy python submission (verdict: Runtime Error):
#from collections import deque, Counter
#from heapq import heapify, heappop, heappush
#from bisect import insort
#from math import gcd
#from decimal import Decimal
#mod = 1000000007
#mod = 998244353
#N = int(input())
#####segfunc#####
def segfunc(x, y):
    return max(x, y)
#################
 
#####ide_ele#####
ide_ele = 0
#################
 
class SegTree:
    """
    init(init_val, ide_ele): 配列init_valで初期化 O(N)
    update(k, x): k番目の値をxに更新 O(logN)
    query(l, r): 区間[l, r)をsegfuncしたものを返す O(logN)
    """
    def __init__(self, init_val, segfunc, ide_ele):
        """
        init_val: 配列の初期値
        segfunc: 区間にしたい操作
        ide_ele: 単位元
        n: 要素数
        num: n以上の最小の2のべき乗
        tree: セグメント木(1-index)
        """
        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
        # 配列の値を葉にセット
        for i in range(n):
            self.tree[self.num + i] = init_val[i]
        # 構築していく
        for i in range(self.num - 1, 0, -1):
            self.tree[i] = self.segfunc(self.tree[2 * i], self.tree[2 * i + 1])
 
    def update(self, k, x):
        """
        k番目の値をxに更新
        k: index(0-index)
        x: update value
        """
        k += self.num
        self.tree[k] = x
        while k > 1:
            self.tree[k >> 1] = self.segfunc(self.tree[k], self.tree[k ^ 1])
            k >>= 1
 
    def query(self, l, r):
        """
        [l, r)のsegfuncしたものを得る
        l: index(0-index)
        r: index(0-index)
        """
        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



### https://qiita.com/ell/items/fe52a9eb9499b7060ed6 heapについて　最大最小の取り出し
N, K = map(int, input().split())
tree = [0 for _ in range(N)]
tree = SegTree(tree, segfunc, ide_ele)
for k in range(N):
  A = int(input())
  A -= 1
  n = tree.query(max(0, A-K), min(N-1, A+K)+1)
  tree.update(A, n+1)
print(tree.query(0, N))
#A = list(map(int, input().split()))
#flag = True
#for k in range(N):
#ans = 0
#print(ans)
#print('Yes')
#print('No')

Fixed submission:
#from collections import deque, Counter
#from heapq import heapify, heappop, heappush
#from bisect import insort
#from math import gcd
#from decimal import Decimal
#mod = 1000000007
#mod = 998244353
#N = int(input())
#####segfunc#####
def segfunc(x, y):
    return max(x, y)
#################
 
#####ide_ele#####
ide_ele = -1
#################
 
class SegTree:
    """
    init(init_val, ide_ele): 配列init_valで初期化 O(N)
    update(k, x): k番目の値をxに更新 O(logN)
    query(l, r): 区間[l, r)をsegfuncしたものを返す O(logN)
    """
    def __init__(self, init_val, segfunc, ide_ele):
        """
        init_val: 配列の初期値
        segfunc: 区間にしたい操作
        ide_ele: 単位元
        n: 要素数
        num: n以上の最小の2のべき乗
        tree: セグメント木(1-index)
        """
        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
        # 配列の値を葉にセット
        for i in range(n):
            self.tree[self.num + i] = init_val[i]
        # 構築していく
        for i in range(self.num - 1, 0, -1):
            self.tree[i] = self.segfunc(self.tree[2 * i], self.tree[2 * i + 1])
 
    def update(self, k, x):
        """
        k番目の値をxに更新
        k: index(0-index)
        x: update value
        """
        k += self.num
        self.tree[k] = x
        while k > 1:
            self.tree[k >> 1] = self.segfunc(self.tree[k], self.tree[k ^ 1])
            k >>= 1
 
    def query(self, l, r):
        """
        [l, r)のsegfuncしたものを得る
        l: index(0-index)
        r: index(0-index)
        """
        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



### https://qiita.com/ell/items/fe52a9eb9499b7060ed6 heapについて　最大最小の取り出し
N, K = map(int, input().split())
tree = [0 for _ in range(400000)]
tree = SegTree(tree, segfunc, ide_ele)
for k in range(N):
  A = int(input())
  n = tree.query(max(0, A-K), min(400000, A+K+1))
  tree.update(A, n+1)
print(tree.query(0, 400000))
#A = list(map(int, input().split()))
#flag = True
#for k in range(N):
#ans = 0
#print(ans)
#print('Yes')
#print('No')