#include <bits/stdc++.h>
using namespace std;
using ll = long long;

const int N = 2e6;

int n, k, c[4004004], mx[4004004], dp[4004004];

int main() {
    cin.tie(0)->sync_with_stdio(0);
    cin >> n >> k;
    for(int i=1;i<=n;i++) {
        int x; cin >> x;
        c[x+N]++, dp[x+N] -= !!dp[x+N];
        mx[x+k+N] = max(mx[x+k+N], ++dp[x+k+N]);
    }

    int ans = 0;
    for(int i=0;i<=2*N;i++) ans = max(ans, c[i]+mx[i]);
    cout << ans;
}