Buggy python submission (verdict: Runtime Error):
import sys
input=sys.stdin.readline

n,k=map(int,input().split())
a=[int(input()) for i in range(n)]


def segfunc(x, y):
    return max(x,y)

def init(init_val):
    # set_val
    for i in range(n):
        seg[i+num-1] = init_val[i]
    # built
    for i in range(num-2, -1, -1):
        seg[i] = segfunc(seg[2*i+1], seg[2*i+2])

def update(k, x):
    k += num - 1
    seg[k] = x
    while k:
        k = (k-1)//2
        seg[k] = segfunc(seg[2*k+1], seg[2*k+2])

def query(p, q):
    if q <= p:
        return ide_ele
    p += num - 1
    q += num - 2
    res = ide_ele
    while q-p>1:
        if p&1 == 0:
            res = segfunc(res, seg[p])
        if q&1 == 1:
            res = segfunc(res, seg[q])
            q -= 1
        p = p//2
        q = (q-1)//2
    if p == q:
        res = segfunc(res, seg[p])
    else:
        res = segfunc(segfunc(res, seg[p]), seg[q])
    return res

# identity element
ide_ele = 0

# num: n以上の最小の2のべき乗
num = 2**(n-1).bit_length()
seg = [ide_ele]*2*num

lst=init([0]*300010)    #aはリスト

ans=0

for i in a:
    l=max(0,i-k)
    r=min(300000,i+k)
    pin=query(l,r+1)+1
    ans=max(ans,pin)
    update(i,pin)


print(ans)


Fixed submission:
import sys
input=sys.stdin.readline

class SegTree:
    def __init__(self, init_val, ide_ele, segfunc):
        self.n = len(init_val)
        self.num = 2**(self.n-1).bit_length()
        self.ide_ele = ide_ele
        self.segfunc = segfunc
        self.seg = [ide_ele]*2*self.num
        # set_val
        for i in range(self.n):
            self.seg[i+self.num] = init_val[i]
        # built
        for i in range(self.num-1, 0, -1):
            self.seg[i] = self.segfunc(self.seg[2*i], self.seg[2*i+1])
 
    def update(self, k, x):
        k += self.num
        self.seg[k] = x
        while k:
            k = k >> 1
            self.seg[k] = self.segfunc(self.seg[2*k], self.seg[2*k+1])
 
    def query(self, l, r):
        if r <= l:
            return self.ide_ele
        l += self.num
        r += self.num
        res = self.ide_ele
        while l < r:
            if r & 1:
                r -= 1
                res = self.segfunc(res, self.seg[r])
            if l & 1:
                res = self.segfunc(res, self.seg[l])
                l += 1
            l = l >> 1
            r = r >> 1
        return res
 
def func(x, y):
    return max(x,y)

seg=SegTree([0]*300001,0,func)

n,k=map(int,input().split())
a=[int(input()) for i in range(n)]

for i in a:
    l=max(0,i-k)
    r=min(300000,i+k)

    pin=seg.query(l,r+1)+1
    seg.update(i,pin)


print(seg.query(0,300001))

Buggy python submission (verdict: Runtime Error):
import sys
input=sys.stdin.readline

n,k=map(int,input().split())
a=[int(input()) for i in range(n)]


def segfunc(x, y):
    return max(x,y)

def init(init_val):
    # set_val
    for i in range(n):
        seg[i+num-1] = init_val[i]
    # built
    for i in range(num-2, -1, -1):
        seg[i] = segfunc(seg[2*i+1], seg[2*i+2])

def update(k, x):
    k += num - 1
    seg[k] = x
    while k:
        k = (k-1)//2
        seg[k] = segfunc(seg[2*k+1], seg[2*k+2])

def query(p, q):
    if q <= p:
        return ide_ele
    p += num - 1
    q += num - 2
    res = ide_ele
    while q-p>1:
        if p&1 == 0:
            res = segfunc(res, seg[p])
        if q&1 == 1:
            res = segfunc(res, seg[q])
            q -= 1
        p = p//2
        q = (q-1)//2
    if p == q:
        res = segfunc(res, seg[p])
    else:
        res = segfunc(segfunc(res, seg[p]), seg[q])
    return res

# identity element
ide_ele = 0

# num: n以上の最小の2のべき乗
num = 2**(n-1).bit_length()
seg = [ide_ele]*2*num

lst=init([0]*300010)    #aはリスト


for i in a:
    l=max(0,i-k)
    r=min(300000,i+k)
    pin=query(l,r+1)+1
    update(i,pin)


print(max(seg))


Fixed submission:
import sys
input=sys.stdin.readline

class SegTree:
    def __init__(self, init_val, ide_ele, segfunc):
        self.n = len(init_val)
        self.num = 2**(self.n-1).bit_length()
        self.ide_ele = ide_ele
        self.segfunc = segfunc
        self.seg = [ide_ele]*2*self.num
        # set_val
        for i in range(self.n):
            self.seg[i+self.num] = init_val[i]
        # built
        for i in range(self.num-1, 0, -1):
            self.seg[i] = self.segfunc(self.seg[2*i], self.seg[2*i+1])
 
    def update(self, k, x):
        k += self.num
        self.seg[k] = x
        while k:
            k = k >> 1
            self.seg[k] = self.segfunc(self.seg[2*k], self.seg[2*k+1])
 
    def query(self, l, r):
        if r <= l:
            return self.ide_ele
        l += self.num
        r += self.num
        res = self.ide_ele
        while l < r:
            if r & 1:
                r -= 1
                res = self.segfunc(res, self.seg[r])
            if l & 1:
                res = self.segfunc(res, self.seg[l])
                l += 1
            l = l >> 1
            r = r >> 1
        return res
 
def func(x, y):
    return max(x,y)

seg=SegTree([0]*300001,0,func)

n,k=map(int,input().split())
a=[int(input()) for i in range(n)]

for i in a:
    l=max(0,i-k)
    r=min(300000,i+k)

    pin=seg.query(l,r+1)+1
    seg.update(i,pin)


print(seg.query(0,300001))