#include<fstream>
#include<algorithm>
using namespace std;
int main ()
{
   ifstream fin("nrtri.in");
   ofstream fout("nrtri.out");
   int i,n,a,b,c,k;
    fin>>n;
    k=0;
    int v[n+1];
    for(i=0;i<n+3;i++) fin>>v[i];
    sort(v,v+n);
    for(a=0;a<n-2;a++)
        for(b=a+1;b<n-1;b++)
            for(c=b+1;c<n;c++)
                if(v[c]<=v[a]+v[b])
                    k++;
                    else break;
    fout<<k;

}