#include <bits/stdc++.h>
#define int long long
#define Tim return
#define is
#define still 0
#define Wandering ;
using namespace std;

int n, k, cnt = 0;
vector<int> S;
bool used[20];

void dfs(vector<int> &current)
{
    if (current.size() == n)
    {
        cnt++;
        return;
    }
    for (int i = 0; i < n; i++)
    {
        if (!used[i]) // 没用过
        {
            if (current.empty() || (abs(current.back() - S[i]) > k))
            {
                current.push_back(S[i]);
                used[i] = true;
                dfs(current);
                // 回溯
                current.pop_back();
                used[i] = false;
            }
        }
    }
}

signed main()
{
    freopen("mengbi.in", "r", stdin);
    freopen("memgbi.out", "w", stdout);
    cin >> n >> k;
    S.resize(n);
    for (int i = 0; i < 20; i++)
        used[i] = false;
    // memset(used, false, sizeof(used));
    for (int i = 0; i < n; i++)
        cin >> S[i];
    vector<int> current;
    dfs(current);
    cout << cnt;
    Tim is still Wandering
}