#include<iostream>
#include<string>
#include<algorithm>
#include<vector>
#include<iomanip>
#include<math.h>
#include<complex>
#include<queue>
#include<deque>
#include<stack>
#include<map>
#include<set>
#include<bitset>
#include<functional>
#include<assert.h>
#include<numeric>
using namespace std;
#define REP(i,m,n) for(int i=(int)(m) ; i < (int) (n) ; ++i )
#define rep(i,n) REP(i,0,n)
typedef long long ll;
typedef pair<int,int> pint;
typedef pair<ll,int> pli;
const int inf=1e9+7;
const ll longinf=1LL<<60 ;
const ll mod=1e9+7 ;

int main(){
    int n,k;
    cin>>n>>k;
    int a[n];
    rep(i,n)cin>>a[i];
    sort(a,a+n);
    ll ans=1;
    rep(i,n/2){
        int r=k-a[n-i-1];
        int cnt=upper_bound(a,a+n-i,r)-a;
        if(cnt==n-i)--cnt;
        cnt=max(0,cnt-i);
        ans=ans*cnt%mod;
    }
    cout<<ans<<endl;
    return 0;
}