#include <fstream>
#include <algorithm>

using namespace std;

ifstream in("nrtri.in");
ofstream out("nrtri.out");
int N, rez;

bool descresc(int a, int b)
{
    return a >= b;
}

int main()
{
    in >> N;
    int v[N];
    for(int i = 0; i < N; ++i)
        in >> v[i];
    sort(v, v + N, &descresc);
    for(int i = 0; i < N - 2; ++i)
    {
        if(v[i] > v[i + 1] + v[i + 2])
            continue;
        for(int j = i + 1; j < N - 1; ++j)
            for(int k = j + 1; k < N; ++k)
                if(v[i] <= v[j] + v[k] && v[j] <= v[i] + v[k] && v[k] <= v[i] + v[j])
                    ++rez;
    }
    out << rez;
    return 0;
}