#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for (int i = 0; i < (n); ++i)
using ll = long long;
using ull = unsigned long long;

int main() {
  cin.tie(nullptr)->sync_with_stdio(false);
  int n, m;
  cin >> n >> m;
  vector<int> a(n);
  rep(i, n) cin >> a[i];
  if (m % 2 == 1) {
    cout << 0 << '\n';
    return 0;
  }
  sort(a.begin(), a.end());
  ll ans = 0;
  rep(i, n) {
    if (binary_search(a.begin(), a.end(), a[i] + m / 2)) ans += n - 2;
  }
  cout << ans << '\n';
  return 0;
}