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