#pragma GCC optimize("Ofast")
#include <bits/stdc++.h>
using namespace std;
typedef long long int ll;
typedef unsigned long long int ull;

mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
ll myRand(ll B) {
    return (ull)rng() % B;
}
inline double time() {
    return static_cast<long double>(chrono::duration_cast<chrono::nanoseconds>(chrono::steady_clock::now().time_since_epoch()).count()) * 1e-9;
}

int main(){
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    int n,m; cin >> n >> m;
    vector<int> a(n);
    set<int> st;
    for (int i = 0; i < n; ++i) {
        cin >> a[i]; a[i] -= 1;
        st.insert(a[i]);
    }
    ll cnt = 0;
    if (m%2 == 0) {
        for (int i = 0; i < n; ++i) {
            if (st.find(a[i]+m/2) != st.end()) cnt += 1;
        }
    }
    cout << cnt*(n-2) << endl;
}