#include<fstream>
using namespace std;
int n,i,j,x,a[801],nr,aux;
int main()
{
    ifstream f("nrtri.in");
    ofstream g("nrtri.out");
    f>>n;
    for(i=1;i<=n;i++)
    f>>a[i];
    for(i=1;i<=n-1;i++)
      for(j=i+1;j<=n;j++)
        if(a[i]>a[j])
        {
            aux=a[i];
            a[i]=a[j];
            a[j]=aux;
        }
        for(i=1;i<=n-2;i++)
          for(j=i+1;j<=n-1;j++)
            {
                for(x=j+1;x<=n;x++)
                if(a[i]+a[j]<=a[x])
                nr++;
            }
          g<<nr<<" ";
          return 0;
}