#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>

using namespace std;

const int N = 2e6;

int a[N], b[N];

int main(){
    memset(a, 0, sizeof a);
    memset(b, 0, sizeof b);

    int n, m, i;
    cin >> n >> m;
    while(n--){
        scanf("%d", &i);
        if(i >= 0) a[i]++;
        else b[-i]++;
    }

    //计算前缀和
    for(i = 1; i < N; i++) {
        a[i] += a[i-1];
        b[i] += b[i-1];
    }

    int res = 0;
    for(i = 0; i <= m; i++){
        //左右挨个走，剩下的步数给另一边折返
        res = max(res, a[i] + b[(m-i)/2]);
        res = max(res, a[i/2] + b[m-i]);
    }

    cout << res;

    return 0;
}