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

using ll = long long;

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

    ll N, M;
    cin >> N >> M;

    vector<ll> A(N);
    for (int i = 0; i < N; i++) cin >> A[i];

    if (M % 2 == 1) {
        cout << 0 << '\n';
        return 0;
    }

    sort(A.begin(), A.end());

    ll half = M / 2;
    ll cnt = 0;

    for (ll a : A) {
        ll b = a + half;
        if (b > M) b -= M;  // mod M (1..M 表現)

        if (binary_search(A.begin(), A.end(), b)) {
            cnt++;
        }
    }

    // 各直径の組を 2 回ずつ数えている
    ll D = cnt / 2;

    ll ans = D * (N - 2);
    cout << ans << '\n';

    return 0;
}