#include <algorithm>
#include <unordered_map>
#include <fstream>
#define DMAX 2000

using namespace std;

ifstream fin ("oite.in");
ofstream fout ("oite.out");

unordered_map <int, int> mySet;
int C, L;
long long sol;
int vals[DMAX];

int main()
{
    fin >> C >> L;
    for (int i = 1; i <= C; ++i)
        fin >> vals[i];

    sort (vals+1, vals+C+1);

    for (int i = 1; i < C; ++i){
        for (int j = i+1; j <= C; ++j)
            sol+=mySet.count (L-vals[i]-vals[j]);

        for (int j = 1; j < i; ++j)
            mySet[vals[i]+vals[j]]++;
        }

    fout<<sol<<'\n';
}