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

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

    int N,M; cin >> N >> M;
    map<int,int> A;
    for(int i=0; i<N; i++){
        int a; cin >> a;
        A[a] = 1;
    }
    if(M%2){cout << 0 << endl; return 0;}

    long long answer = 0;
    for(auto[a,c] : A){
        if(c == 0) continue;
        if(A[a+M/2] == 1) answer += N-2; 
    }
    cout << answer << endl;
}