#include <fstream>

using namespace std;

int main()
{
    ifstream in("nrtri.in");
    ofstream out("nrtri.out");
    long long i,n,l,m,q,j,cnt=0,aux,v[30002];
    in>>n;
    for(i=1;i<=n;i++) in>>v[i];
    for(i=1;i<=n;i++)
    for(j=i+1;j<=n;j++)
    {
        if (v[i]>=v[j])
            {
                aux=v[i];
                v[i]=v[j];
                v[j]=aux;
            }
    }

    for(l=1;l<=n-2;l++)
    for(m=l+1;m<=n-1;m++)
    for(q=m+1;q<=n;q++)
    {
        if(a[q] <= a[l] + a[m])
                    cnt=cnt+1;
                else
                    break;
            }
    }
    out<<cnt;
    return 0;
}