#include<fstream>
using namespace std;

int main()
{
    int i,n,v[1001],schimb,aux,a,b,c,k;
    ifstream cin("ntri.in");
    ofstream cout("ntri.out");
    cin>>n;
    k=0;
    for(i=0;i<n;i++) cin>>v[i];
    do
    {
        schimb=1;
        for(i=0;i<n;i++)
        {
            if(v[i]>v[i+1])
            {
                aux=v[i];
                v[i]=v[i+1];
                v[i+1]=aux;
                schimb=0;
            }
        }
    }while(schimb==0);
    for(a=0;a<n-2;a++)
    {
        for(b=a+1;b<n-2;b++)
        {
            for(c=b+1;c<n;c++)
            {
                if(v[a]<=v[b]+v[c] && v[b]<=v[a]+v[c] && v[c]<=v[a]+v[b])
                {
                    k++;
                }
            }
        }
    }
    cout<<k;
}