//#include <iostream>
#include <fstream>
#include <unordered_map>
using namespace std;
unordered_map <long long,long long> sum;
long long v[1500],n,l,suma,var;
int main()
{
    ifstream cin("oite.in");
    ofstream cout("oite.out");
    cin>>n>>l;
    for(int i=1;i<=n;i++){
        cin>>v[i];
    }
    for(int i=1;i<=n;i++){
        for(int j=i+1;j<=n;j++){
                var+=sum[l-v[i]-v[j]];
        }
        for(int j=i-1;j>=1;j--)
            sum[v[i]+v[j]]++;
    }
    cout<<var;
    return 0;
}
//13 1 12 1 12 1