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

ifstream fin("nrtri.in");
ofstream fout("nrtri.out");

int main()
{
    int n,V[801],tr = 0;
    fin>>n;
    for(int i = 1;i<=n;i++)
    {
        fin>>V[i];
    }
    for(int a = 1;a<=n;a++)
    {
        for(int b = a+1;b<=n;b++)
        {
            for(int c = b+1;c<=n;c++)
            {
                if(V[a]+V[b]>=V[c] && V[b]+V[c]>=V[a] && V[c]+V[a]>=V[b])
                    tr++;
            }
        }
    }
    fout<<tr;

}