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 <iostream>
#include <algorithm>
#include <iomanip>
#include <string>
#include <atcoder/all>
#include <vector>
#include <math.h>
#include <queue>
#include <deque>
#include <stack>
#include <map>
#include <set>
#define PI 3.14159265359
using namespace std;
using namespace atcoder;
using mint = modint998244353;
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int, int> pai;
typedef pair<ll, ll> pal;
const int MOD = 1e9+7;
const int MODD = 998244353;
const ll LLINF = 1e18;

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

int e() { return -1; }

segtree<int, op, e> seg(300001);
vector<int> dp(300000);

int main(){
	int n, k;
	cin >> n >> k;
	vector<int> a(n);
	for (int i = 0; i < n; i++) cin >> a[i];

	dp[0] = 1;
	seg.set(a[0], 1);
	for (int i = 1; i < n; i++){
		dp[i] = max(1, seg.prod(max(1, a[i]-k), min(n, a[i]+k)+1)+1);
		seg.set(a[i], dp[i]);
	}
	int ans = 0;
	for (int i = 0; i < n; i++){
		ans = max(ans, dp[i]);
	}
	cout << ans << endl;
	return 0;
}