import java.io.BufferedReader; import java.io.BufferedWriter; import java.io.Closeable; import java.io.FileInputStream; import java.io.FileWriter; import java.io.IOException; import java.io.InputStreamReader; import java.io.PrintWriter; import java.lang.reflect.Array; import java.util.*; public class Main implements Runnable { static ContestScanner in; static Writer out; public static void main(String[] args) { new Thread(null, new Main(), "", 16 * 1024 * 1024).start(); } public void run() { Main main = new Main(); try { in = new ContestScanner(); out = new Writer(); main.solve(); out.close(); in.close(); } catch (IOException e) { e.printStackTrace(); } } void solve() throws IOException { long mod = 1000000007; int n = in.nextInt(); int k = in.nextInt(); long[] a = new long[n]; for (int i = 0; i < a.length; i++) { a[i] = in.nextLong(); } Arrays.sort(a); long ans = 1; int i = n - 1; int j = 0; for (j = 0; i >= 0; i--, j++) { if (a[i] * 2 <= k) break; int id = Arrays.binarySearch(a, k - a[i]); // if (id < 0) System.out.println((id) + ":" + (-1 - id)); // else System.out.println(id); if (id == -1) { System.out.println(0); return; } if (id < 0) id = -id - 2; id += 1; if (id - j < 0) { System.out.println(0); return; } ans = (ans * (id - j)) % mod; } for (int l = 0; l < (n - j * 2) / 2 - 1; l++, i-=2) { ans = ans * i % mod * (i + 1) % mod * modinv(2, mod) % mod * modinv(l + 2, mod) % mod; } System.out.println(ans); } long modinv(long n, long mod){ return modpow(n, mod-2, mod); } long modpow(long n, long a, long mod){ long res = 1; while(a > 0){ if((a&1)==1) res = (res * n) % mod; n = n * n % mod; a >>= 1; } return res; } } @SuppressWarnings("serial") class MultiSet extends HashMap{ @Override public Integer get(Object key){return containsKey(key)?super.get(key):0;} public void add(T key,int v){put(key,get(key)+v);} public void add(T key){put(key,get(key)+1);} public void sub(T key){final int v=get(key);if(v==1)remove(key);else put(key,v-1);} public MultiSet merge(MultiSet set) {MultiSets,l;if(this.size()e:s.entrySet())l.add(e.getKey(),e.getValue());return l;} } class Writer extends PrintWriter{ public Writer(String filename)throws IOException {super(new BufferedWriter(new FileWriter(filename)));} public Writer()throws IOException{super(System.out);} } class ContestScanner implements Closeable{ private BufferedReader in;private int c=-2; public ContestScanner()throws IOException {in=new BufferedReader(new InputStreamReader(System.in));} public ContestScanner(String filename)throws IOException {in=new BufferedReader(new InputStreamReader(new FileInputStream(filename)));} public String nextToken()throws IOException { StringBuilder sb=new StringBuilder(); while((c=in.read())!=-1&&Character.isWhitespace(c)); while(c!=-1&&!Character.isWhitespace(c)){sb.append((char)c);c=in.read();} return sb.toString(); } public String readLine()throws IOException{ StringBuilder sb=new StringBuilder();if(c==-2)c=in.read(); while(c!=-1&&c!='\n'&&c!='\r'){sb.append((char)c);c=in.read();} return sb.toString(); } public long nextLong()throws IOException,NumberFormatException {return Long.parseLong(nextToken());} public int nextInt()throws NumberFormatException,IOException {return(int)nextLong();} public double nextDouble()throws NumberFormatException,IOException {return Double.parseDouble(nextToken());} public void close() throws IOException {in.close();} }