#include<algorithm>
#include<complex>
#include<ctype.h>
#include<iomanip>
#include<iostream>
#include<map>
#include<math.h>
#include<numeric>
#include<queue>
#include<set>
#include<stack>
#include<stdio.h>
#include<string>
#include<string>
#include<vector>

using namespace std;
typedef long long ll;

#define FOR(i,a,b) for(ll i=(a);i<(b);++i)
#define ALL(v) (v).begin(), (v).end()
#define p(s) cout<<(s)<<endl
#define p2(s, t) cout << (s) << " " << (t) << endl
#define br() p("")
#define pn(s) cout << (#s) << " " << (s) << endl
#define p_yes() p("YES")
#define p_no() p("NO")

template < typename T >
void vprint(T &V){
	for(auto v : V){
    	cout << v << " ";
	}
	cout << endl;
}

const ll mod = 1e9 + 7;
const ll inf = 1e18;

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

    // input
    ll N, K;
    cin >> N >> K;
    
    vector<ll> A(N);
    FOR(i, 0, N){
        cin >> A.at(i);
    }
    sort(ALL(A));

    vector<ll> B(N);
    B[0] = 0;
    FOR(i, 1, N){
        ll a = A[i];
        ll b = K - a;
        auto it = upper_bound(A.begin(), A.begin()+i, b);
        ll over_num = distance(it, A.end());
        ll num = N - over_num;
        B[i] = num;
    }

    ll answer = 1;
    FOR(i, 0, N/2){
        ll index = N - 1 - i;
        answer *= B[index] - i;
        
        if(answer <= 0){
            p(0);
            return 0;
        }
    }
    
    p(answer);

    return 0;
}