#include<bits/stdc++.h>
#define IOS ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);
#define endl '\n'
#define fixed(s) fixed<<setprecision(12)<<s
//#define int long long
 
using namespace std;
 
typedef pair<int, int> PII;
typedef long long ll;
typedef pair<ll, PII> PLII;

const int N = 4000010, P = 1000000;

int n, k;
int a[N];
int cnt[N];
vector<int> g[N];
int t_num[N];

int main()
{
	IOS
	cin >> n >> k;
	int t_ans = 0;
	for(int i = 1; i <= n; i ++)
	{
		cin >> a[i];
		t_num[a[i] + P] ++;
		t_ans = max(t_ans, t_num[a[i] + P]);
	}
	
	if(k == 0)
	{
		cout << t_ans << endl;
		return 0;
	}
	
	for(int i = 1; i <= n; i ++)
	{
		cnt[a[i] + P] ++;
		
		if(a[i] - k + P >= 0 && a[i] - k + P <= 2000000)g[a[i] + P].push_back(cnt[a[i] - k + P]);
		g[a[i] + P].push_back(-1);
		
		if(a[i] - k + P >= 0 && a[i] - k + P <= 2000000)cnt[a[i] - k + P] = 0;
	}
	int ans = -2e9;
	for(int i = -1000000; i <= 1000000; i ++)
	{
		if(i - k + P >= 0 && i - k + P <= 2000000)g[i + P].push_back(cnt[i - k + P]);
		
		int res = 0;
		for(int j = 0; j < g[i + P].size(); j ++)
		{
			if(j)g[i + P][j] = max(g[i + P][j], g[i + P][j - 1] + g[i + P][j]);
			res = max(res, g[i + P][j]);
		}
		ans = max(ans, res + t_num[i + P]);
	}
	cout << ans << endl;
	
	return 0;
}