#include <bits/stdc++.h>
#define rep(i,n) for(int i = 0; i < (n); ++i)
#define srep(i,s,t) for (int i = s; i < t; ++i)
#define drep(i,n) for(int i = (n)-1; i >= 0; --i)
using namespace std;
typedef long long int ll;
typedef pair<int,int> P;
#define yn {puts("Yes");}else{puts("No");}
#define MAX_N 200005

ll mod_pow(ll x, ll n, ll mod){ // x ^ n % mod
    ll res = 1;
    while(n > 0){
        if (n & 1) res = res * x % mod;
        x = x * x % mod;
        n >>= 1;
    }
    return res;
}

int main() {
    int n; cin >> n;
    int K; cin >> K;
    int a[n] = {};
    rep(i,n) cin >> a[i];
    sort(a, a+n);
    ll ans = 1;
    const ll MOD = 1000000007;
    ll cnt = 0;
    ll l = 0;
    int f[n] = {};
    drep(i,n){
        int x = K - a[i];
        if(f[i] == 0){
            cnt++;
            f[i] = 1;
        }
        while(f[l] == 0){
            if(a[l] <= x){
                cnt++;
                f[l] = 1;
                l++;
            }else{
                break;
            }
        }
        ans *= cnt - 1;
        ans %= MOD;
        cnt -= 2;
        if(i == n/2) break;
    }

    cout << ans << endl;
    return 0;
}