#include <bits/stdc++.h>
using namespace std;

typedef long long ll;
#define FOR(i, a, b) for (int i = a; i < (b); i++)
#define RFOR(i, a, b) for (int i = a; i >= (b); i--)
#define range(a) a.begin(), a.end()
#define endl "\n"
#define Yes() cout << "Yes" << endl
#define No() cout << "No" << endl
#define pb push_back
int dx[4] = {-1, 0, 1, 0};
int dy[4] = {0, -1, 0, 1};
using P = pair<int, int>;
const long long INFL = LLONG_MAX;
const int INFI = INT_MAX;
template<class T>bool chmin(T &a, const T &b) { if(a > b) {a = b; return true; } else return false; }
template<class T>bool chmax(T &a, const T &b) { if(a < b) {a = b; return true; } else return false; }

int main(void){
	ios::sync_with_stdio(0);
	cin.tie(0);
	int N, M;
	cin >> N >> M;
	map<int, int> mp;
	for(int i = 0; i < N; i++){
		int a;
		cin >> a;
		mp[a]++;
	}
	if(M % 2 == 1){
		cout << 0 << endl;
		return 0;
	}
	ll ans = 0LL;
	for(auto [a, b]: mp){
		if(a > M / 2) break;
		int c = a + M / 2;
		ans += (ll)b * (ll)mp[c] * (ll)(N - b - mp[c]);
	}
	cout << ans << endl;

	return 0;
}