#include <fstream>
#include <algorithm>
using namespace std;
ifstream fin ("nrtri.in");
ofstream fout ("nrtri.out");
int n,v[8010],sum,i,j,p,sol;
int main () {
    fin>>n;
    for(i=1;i<=n;i++)
        fin>>v[i];
    sort(v+1,v+n+1);
    for(i=1;i<=n-2;i++){
        for(j=i+1;j<=n-1;j++){
            for(p=j+1;p<=n;p++)
                if(v[i]+v[j]>=v[p] && v[i]+v[p]>=v[j] && v[j]+v[p]>=v[i])
                    sol++;
                else
                    break;
        }
    }
    fout<<sol;

}