/// *** --- ||| In the name of ALLAH ||| --- *** /// #include<bits/stdc++.h> using namespace std; #define fastio() ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0); #define fraction() cout.unsetf(ios::floatfield); cout.precision(10); cout.setf(ios::fixed,ios::floatfield); #define file() freopen("input.txt","r",stdin);freopen("output.txt","w",stdout); #define endl '\n' #define ll long long #define int long long #define all(a) (a).begin(),(a).end() #define rall(a) (a).rbegin(),(a).rend() #define sz(x) (int)x.size() #define mem(a,b) memset(a, b, sizeof(a) ) #define sq(a) ((a) * (a)) #define unq(x) {x.erase(unique(x.begin(),x.end()),x.end());} const double PI = acos(-1); const double eps = 1e-9; const int inf = 2000000000; const int MX = 2e5+123; const ll infLL = 9000000000000000000; const int MOD = 1e9+9; // //debug template<typename F,typename S>ostream&operator<<(ostream&os,const pair<F,S>&p){return os<<"("<<p.first<<", "<<p.second<<")";} template<typename T>ostream&operator<<(ostream&os,const vector<T>&v){os<<"{";for(auto it=v.begin();it!=v.end();++it){if(it!=v.begin())os<<", ";os<<*it;}return os<<"}";} template<typename T>ostream&operator<<(ostream&os,const set<T>&v){os<<"[";for(auto it=v.begin();it!=v.end();++it){if(it!=v.begin())os<<",";os<<*it;}return os<<"]";} template<typename T>ostream&operator<<(ostream&os,const multiset<T>&v) {os<<"[";for(auto it=v.begin();it!=v.end();++it){if(it!=v.begin())os<<", ";os<<*it;}return os<<"]";} template<typename F,typename S>ostream&operator<<(ostream&os,const map<F,S>&v){os<<"[";for(auto it=v.begin();it!=v.end();++it){if(it!=v.begin())os<<", ";os<<it->first<<" = "<<it->second;}return os<<"]";} #define dbg(args...) do {cerr << #args << " : "; faltu(args); } while(0) void faltu(){cerr << endl;} template<typename T>void faltu(T a[],int n){for(int i=0;i<n;++i)cerr<<a[i]<<' ';cerr<<endl;} template<typename T,typename...hello>void faltu(T arg,const hello&...rest){cerr<<arg<<' ';faltu(rest...);} //#else //#define dbg(args...) void solve (int CaseNo) { int n, d; cin >> n >> d; vector<int> h(n); for (int i = 0; i < n; i++) cin >> h[i]; int mx = (1 << n); vector<vector<int>> dp(mx, vector<int> (n)); /// dp[mask][top block or last block] // base case for (int i = 0; i < n; i++) { dp[1 << i][i] = 1; } // dbg (dp); for (int mask = 0; mask < mx; mask++) { for (int j = 0; j < n; j++) { for (int k = 0; k < n; k++) { if ((mask & (1 << k)) == 0 && h[k] <= (h[j] + d)) { int newMask = mask | (1 << k); dp[newMask][k] += dp[mask][j]; dp[newMask][k] %= MOD; } } } } int ans = 0; for (int i= 0; i < n; i++) { ans += dp[mx-1][i]; } cout << ans << endl; } int32_t main() { fastio(); // srand(time(NULL)); int testcases = 1; // cin >> testcases; for (int tt = 1; tt <= testcases; tt++) { solve (tt); } return 0; }