#include <bits/stdc++.h>
using namespace std;
using int64 = long long;
typedef pair<int, int> P;
const int mod = 1e9 + 7;

int main(){
    int n, k;
    cin >> n >> k;
    vector<int> a(n);
    for(int i = 0; i < n; i++) cin >> a[i];
    sort(a.begin(), a.end());
    int64 ans = 1, l = 0, cnt = 0;
    for(int r = n - 1; r >= n / 2; r--){
        while(l < n && a[l] + a[r] <= k){
            // cout << " " << l << " " << r << " " << a[l] + a[r] << endl;
            l++; cnt++;
        }
        if(r < l) cnt--;
        // cout << r << ' ' << l << ' ' << cnt << endl;
        ans = (ans * cnt) % mod;
        cnt--;
    }
    cout << ans << endl;
}