#include <iostream>
#include <cstdio>
#include <algorithm>
using namespace std;

const int dmax = 800;

int v[dmax + 1];

int answer;
int N;

int main()
{
    freopen("nrtri.in", "r", stdin);
    freopen("nrtri.out", "w", stdout);

    int i, j, k;
    bool GASIT = true;

    scanf("%d", &N);
    for(i = 1; i <= N; i++) scanf("%d", &v[i]);

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

    for(i = 1; i <= N; i++)
        for(j = i+1; j <= N; j++)
        {
            GASIT = true;

            for(k = j+1; k <= N && GASIT == true; k++)
                //CONDITIE FORMARE TRIUNGHI
                if(v[i] + v[j] >= v[k] && v[j] + v[k] >= v[i] && v[i] + v[k] >= v[j]) answer++;
                else
                    GASIT = false;
        }

    printf("%d", answer);

    return 0;
}