#include <fstream>
#include <algorithm>
using namespace std;
int a[805];
int main()
{
    ifstream f("nrtri.in");
    ofstream g("nrtri.out");

    int n, i, k=0, j, p;
    f >> n;
    for(i=1; i<=n; i++) f >> a[i];
    sort(a+1, a+n+1);
    for(i=1; i<=n; i++)
        for(j=i+1; j<=n; j++)
            for(p=j+1; p<=n; p++)
            if((a[i]+a[j]>=a[p]) && (a[p]+a[i]>=a[j]) && (a[j]+a[p] >=a[i])) k++;
            else break;
    g << k;
}