#include <fstream>
#include <algorithm>
using namespace std;

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

int a[803],n,i,j,k,cont;
//fout<<a[i]<<" "<<a[j]<<" "<<a[k]<<" \n";
int main()
{
    fin>>n;
    for(i=1; i<=n; i++)
        fin>>a[i];
    sort(a+1, a+n+1);
    for(i=n; i>=3; i--)
        for(j=i-1; j>=2; j--)
            for(k=j-1; k>=1; k--)
                if(a[i]<=a[j]+a[k])
                    cont++;
    fout<<cont;


    fin.close();
    fout.close();
    return 0;
}