#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;
    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++){
            x=v[i]+v[j];
            st=1;
            dr=n;
            while(dr-st>1){
                mij=st+(dr-st)/2;
                if(v[mij]>x)
                dr=mij;
                else
                st=mij;
            }
            if(st!=i && st!=j && v[st]+v[i]>=v[j] && v[st]+v[j]>=v[i] && v[i]+v[j]>=v[st])
            ans++;
        }
    }
    fout<<ans;
}