#include <iostream>
#include <vector>
#include <algorithm>
#include <cmath>
#include <set>
#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
using ll = long long;
using mint = modint998244353;
using vi = vector<int>;
using vvi = vector<vi>;
using vvvi = vector<vvi>;
using vll = vector<ll>;
using vvll = vector<vll>;
using vvvll = vector<vvll>;
using vmi = vector<mint>;
using vvmi = vector<vmi>;
using vvvmi = vector<vvmi>;
#define all(a) (a).begin(), (a).end()
#define rep2(i, m, n) for (int i = (m); i < (n); ++i)
#define rep(i, n) rep2(i, 0, n)
#define drep2(i, m, n) for (int i = (m)-1; i >= (n); --i)
#define drep(i, n) drep2(i, n, 0)

void solve(){
    
}

int main(){
    int n, m; cin >> n >> m;
    set<int> st; rep(i, n){
        int a; cin >> a; st.insert(a);
    }
    if(m%2 != 0){
        cout << 0 << endl;
        return 0; 
    }
    ll ans = 0;
    while(st.size() > 0){
        int b = *st.begin();
        if(st.count(b + m/2)){
            ans += (ll)(n-2);
        }
        st.erase(b);
    }cout << ans << endl;

    return 0;
}