Problem:
Score : 400 points

Problem Statement

You are given a sequence A_1, A_2, ..., A_N and an integer K.

Print the maximum possible length of a sequence B that satisfies the following conditions:

B is a (not necessarily continuous) subsequence of A.

For each pair of adjacents elements of B, the absolute difference of the elements is at most K.

Constraints

1 \leq N \leq 300,000

0 \leq A_i \leq 300,000

0 \leq K \leq 300,000

All values in input are integers.

Input

Input is given from Standard Input in the following format:

N K
A_1
A_2
:
A_N

Output

Print the answer.

Sample Input 1

10 3
1
5
4
3
8
6
9
7
2
4

Sample Output 1

7

For example, B = (1, 4, 3, 6, 9, 7, 4) satisfies the conditions.

It is a subsequence of A = (1, 5, 4, 3, 8, 6, 9, 7, 2, 4).

All of the absolute differences between two adjacent elements (|1-4|, |4-3|, |3-6|, |6-9|, |9-7|, |7-4|) are at most K = 3.

Solution in C++ (GCC 9.2.1 with AC Library v1.1) (judge verdict: Runtime Error)

#include <bits/stdc++.h>
#include <atcoder/all>
#define rep(i,n) for (int i = 0; i < (n); i++)
using namespace std;
using namespace atcoder;
using ll = long long;
using P = pair<int,int>;

int op(int a, int b){
	return max(a, b);
}

int e(){
	return 0;
}

int main(){
	int n, k;
	cin>>n>>k;
	vector<int> a(n);
	rep(i, n) cin>>a[i];

	segtree<int, op, e> seg(n);
	rep(i, n){
		int mx=seg.prod(max(0, a[i]-k), min(n, a[i]+k+1));
		seg.set(a[i], mx+1);
	}

	int ans=seg.get(a[n-1]);
	cout<< ans <<endl;
	return 0;
}