// fac eu sortarea
#include <cstdio>
#include <algorithm>

using namespace std;

int a[801];
int n;
int result;

void read() {
    freopen ("nrtri.in", "r", stdin);
    scanf ("%d", &n);
    for (int i = 1; i <= n; ++i)
        scanf ("%d", &a[i]);
}

void solve() {
    sort(a + 1, a + n + 1);

    int i, j, k;
    // continua tu
    for(i = 1; i <= n; ++i)
        for(j = i + 1; j <= n; ++j)
            for(k = j + 1; k <= n; ++k)// de ce ai j = 1 si k = 1? trebuie sa ai i < j < k
                if(a[i] + a[j] >= a[k])++result;//?da altceva? afisezi result si mai trebuie sa-l declari

}//bun?da

int main() {
    read();
    solve();
    freopen("nrtri.out","w",stdout);
    printf("%d ",result);
}