#include <iostream>
#include <fstream>
using namespace std;
int main()

{
    int n,i,v[801],j,k,nr=0,inj,gata,OK,aux;
    fstream f("nrtri.in",ios::in);
    fstream g("nrtri.out",ios::out);
    f>>n;
    for(i=1;i<=n;i++)
        f>>v[i];


inj=n;
while(inj>1)
{

    inj=inj/2;
    do{gata=1;
    for(i=1;i<=n-inj;i++)
        if(v[i]>v[i+inj])
        {
            aux=v[i];
            v[i]=v[i+inj];
            v[i+inj]=aux;
            gata=0;
        }
    }while(!gata);
}


    for(i=1;i<=n-2;i++)

            for(j=i+1;j<=n-1;j++)
           {OK=1;
           for(k=j+1;((k<=n)&&(OK==1));k++)
        if((v[i]+v[j]>=v[k]) && (v[i]+v[k]>=v[j]) && (v[k]+v[j]>=v[i]))
        nr++;
        else
            OK=0;
           }


    g<<nr;

}