#include<fstream>

using namespace std;

int n,a[100],p;
int main()
{
    ifstream fin("nrtri.in");
    ofstream fout("nrtri.out");
int i,j,k;
fin>>n;
for(i = 1; i <= n; i++)
fin>>a[i];
for(i = 1; i <= n; i++)
{
      for(j = i+1;j <= n; j++)
      {
            for(k = j+1;k <= n;k++)
            if(a[i]+a[j]>=a[k] && a[k]+a[i]>=a[j] && a[j]+a[k] >=a[i])
            p++;
      }
}
fout<<p;

fin.close();
fout.close();

return 0;

}