#include <iostream>
#include <fstream>
using namespace std;

int main()
{ifstream fin("nrtri.in");
 ofstream fout("nrtri.out");
 int a[100000],N,i,j,k,l=0;
 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[i]+a[k]>=a[j] && a[j]+a[k]>=a[i])
             l++;}}}

fout<<l;
}