#include <iostream>
#include <fstream>
#include <vector>
#include <algorithm>

using namespace std;

ifstream f("nrtri.in");
ofstream g("nrtri.out");

vector<int> B;
int N;


int main()
{
    f>>N;
    int n;
    for(int i=0;i<N;i++)
    {
        f>>n;
        B.push_back(n);
    }
    sort(B.begin(),B.end());

    long nrtri=0;

    for(int i=N-1;i>1;i--)        ///selectam primul bat
    {
        for(int j=i-1;j>0;j--)  ///selectam al doilea bat
        {
            bool Stop=0;
            for(int k=j-1;k>=0 && !Stop;k--) ///selectam al treilea bat si vf inegalitatea triunghiulara
            {
                if(B[i]>B[j]+B[k]) Stop=1;
                if (!Stop) nrtri++;
            }
        }
    }

    g<<nrtri;

    return 0;
}