Problem p02534 (python)

Fixed submission:
print("ACL"*int(input()))

Buggy submission (verdict: Runtime Error):
class SegmentTree:
    def __init__(self, data, default=0, func=max):
        self._default = default
        self._func = func
        self._len = len(data)
        self._size = _size = 1 << (self._len - 1).bit_length()
        self.data = [default] * (2 * _size)
        self.data[_size:_size + self._len] = data
        for i in reversed(range(_size)):
            self.data[i] = func(self.data[i + i], self.data[i + i + 1])
    def __delitem__(self, idx):
        self[idx] = self._default
    def __getitem__(self, idx):
        return self.data[idx + self._size]
    def __setitem__(self, idx, value):
        idx += self._size
        self.data[idx] = value
        idx >>= 1
        while idx:
            self.data[idx] = self._func(self.data[2 * idx], self.data[2 * idx + 1])
            idx >>= 1
    def __len__(self):
        return self._len
    def query(self, start, stop):
        start += self._size
        stop += self._size
        res_left = res_right = self._default
        while start < stop:
            if start & 1:
                res_left = self._func(res_left, self.data[start])
                start += 1
            if stop & 1:
                stop -= 1
                res_right = self._func(self.data[stop], res_right)
            start >>= 1
            stop >>= 1
        return self._func(res_left, res_right)
    def __repr__(self):
        return "SegmentTree({0})".format(self.data)

import sys
input=sys.stdin.readline
n,k=map(int,input().split())
M=1048576
s=SegmentTree([0]*M)
for i in range(n):
    a=int(input())
    s[a]=1+s.query(max(a-k,0),a+k+1)
print(s.query(0,M))

Buggy submission (verdict: Runtime Error):
class SegmentTree:
    def __init__(self, data, default=0, func=max):
        self._default = default
        self._func = func
        self._len = len(data)
        self._size = _size = 1 << (self._len - 1).bit_length()
        self.data = [default] * (2 * _size)
        self.data[_size:_size + self._len] = data
        for i in reversed(range(_size)):
            self.data[i] = func(self.data[i + i], self.data[i + i + 1])
    def __delitem__(self, idx):
        self[idx] = self._default
    def __getitem__(self, idx):
        return self.data[idx + self._size]
    def __setitem__(self, idx, value):
        idx += self._size
        self.data[idx] = value
        idx >>= 1
        while idx:
            self.data[idx] = self._func(self.data[2 * idx], self.data[2 * idx + 1])
            idx >>= 1
    def __len__(self):
        return self._len
    def query(self, start, stop):
        start += self._size
        stop += self._size
        res_left = res_right = self._default
        while start < stop:
            if start & 1:
                res_left = self._func(res_left, self.data[start])
                start += 1
            if stop & 1:
                stop -= 1
                res_right = self._func(self.data[stop], res_right)
            start >>= 1
            stop >>= 1
        return self._func(res_left, res_right)
    def __repr__(self):
        return "SegmentTree({0})".format(self.data)

import sys
z=sys.stdin.readline
n,k=map(int,z().split())
M=1048576
s=SegmentTree([0]*M)
for i in range(n):
    a=int(z())
    v,w=0,M
    if a>k:v=a-k
    if a+k+1<M:w=a+k+1
    s[a]=1+s.query(v,w)
print(s.query(0,M))