#include <iostream>
#include <fstream>
using namespace std;

int x[810];

void ordonare_crescator(int x[],int n){

    int i,j,aux;
    for(i=1;i<n;i++)
        for(j=i;j<=n;j++)
            if(x[i]>x[j]){
                aux=x[i];
                x[i]=x[j];
                x[j]=aux;
            }


}

int main()
{
    ifstream fin ("nrtri.in");
    ofstream fout ("nrtri.out");
    int n,k=0,contor=0,i,j;
    fin>>n;
    for(i=1;i<=n;i++){
        fin>>x[i];
    }

    ordonare_crescator(x,n);


    for(k=n;k>=1;k--)
    for(i=1;i<n;i++){
        for(j=i+1;j<k;j++){
                //cout<<" *** "<<i<<" "<<j<<" "<<k<<endl;
            if(x[i]+x[j]>=x[k] && x[i]+x[k]>=x[j] && x[j]+x[k]>=x[i] && k!=i && i!=j)
               // cout<<x[i]<<" "<<x[j]<<" "<<x[k]<<endl;
               contor++;
        }

    }
    fout<<contor;








    return 0;
}