#include <algorithm>
#include <iostream>
using namespace std;
constexpr int M = 1000000007;
int main() {
    int n, k; cin >> n >> k;
    int a[n];for (int i = 0; i < n; i++) cin >> a[i];
    sort(a, a+n);
    long long ans = 1;
    int i = 0, j = n-1;
    while (i < j) {
        while (i < j && a[i] + a[j] <= k) i++;
        if (i < n - j) { cout << 0 << endl; return 0; }
        ans = ans * (i - (n - j - 1)) % M;
        j--;
        // cerr << i << ' ' << j << ' ' << ans << endl;
    }
    int m = (j + 1 - (n - j - 1)) / 2;
    // cerr << m << endl;
    while (m > 0) { ans = ans * (2 * m - 1) % M; m--; }
    cout << ans << endl;
}