#include <fstream>
#include <algorithm>
using namespace std;
ifstream fin("nrtri.in");
ofstream fout("nrtri.out");
int v[801];
int main()
{
    int n,i,j,x,st,dr,mij,ans=0,k;
    fin>>n;
    for(i=1;i<=n;i++)
    fin>>v[i];
    sort(v+1,v+n+1);
    //sortare stl fiindca e rapida si e doar o linie de scris 
    for(i=1;i<=n;i++){
        for(j=i+1;j<=n;j++){
            for(k=j+1;k<=n;k++){
                if(v[i]+v[j]>=v[k] && v[k]+v[j]>=v[i] && v[i]+v[k]>=v[j])
                ans++;
            }
        }
    }
    fout<<ans;
}