# include <fstream>
# include <iostream>
using namespace std;
ifstream f("nrtri.in");
ofstream g("nrtri.out");
int n,a[100],nr,i,j,k;

int main()
{
    f>>n;
    for(i=1;i<=n;i++)
        f >> a[i];
    for(i=1;i<=n-2;++i)
        for(j=i+1;j<=n-1;++j)
            for(k=j+1;k<=n;++k)
            {
                if(a[i]+a[k]>=a[j] && a[i]+a[j]>=a[k] &&a[k]+a[j]>=a[i])
                    nr++;
            }
  g<<nr;
  f.close();
  g.close();
return 0;
}