#include <iostream>
#include <vector>
#include <string>
#include <algorithm>
#include <cstdio>
#include <cstring>
#include <cmath>
using namespace std;
using ll = long long;

constexpr int P = 1000000007;

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);

    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());

    ll r = 1;
    int j = 0;
    for (int i = n - 1; i >= n / 2; i--) {
        for (; j < n; j++) {
            if (a[i] + a[j] > k) break;
        }
        int t = min(i, j) - (n - 1 - i);
        if (t <= 0) {
            r = 0;
            break;
        }
        r = r * t % P;
    }

    cout << r << endl;

    return 0;
}