#include<bits/stdc++.h>
using namespace std;

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

int v[805];

int main()
{
    int n, i, j, k, cntr = 0;
    fin>> n;
    for(i = 1; i <= n; i++)
        fin>> v[i];


    sort(v+1, v+n+1);

    for(i = 1; i <= n-2; i++)
    {
        for(j = i+1; j <= n-1; j++)
        {
           for(k = i+2; k <= n; k++)
           {
               if(v[i]+v[j] > v[k])
                cntr++;
           }
        }
    }
    fout<< cntr;
    fin.close();
    fout.close();
    return 0;
}