#include <fstream>
#include <algorithm>
using namespace std;
ifstream cin("nrtri.in");
ofstream cout("nrtri.out");
int N,v[805];
int main()
{
    cin>>N;
    for(int i=1;i<=N;i++){
        cin>>v[i];
    }
    sort(v+1,v+N+1);
    int solutie=0;
    for(int i=1;i<=N;i++){
        for(int j=i+1;j<=N;j++){
            for(int d=j+1;d<=N;d++){
                if(v[i] + v[j] >= v[d]){
                    solutie++;
                }
            }
        }
    }
    cout<<solutie;
}