#include <iostream>
#include <fstream>

using namespace std;

int v[100];

int main()
{int N, o=1, r, pas, i , j, x, p=0 , aux;
ifstream in("nrtri.in");
ofstream out("nrtri.out");

in>>N;


for (i=1;i<=N;i++)
    in>>v[i];

for (i=1;i<N;i++)
    for (j=i+1;j<=N;j++)
        if (v[i]>v[j])
        {
            aux=v[i];
            v[i]=v[j];
            v[j]=aux;
        }

    for (i=1;i<=N-2;i++){
        for (j=i+1;j<=N-1;j++){
            x=v[i]+v[j];
            r=0;
            pas=1<<10;


            while (pas!=0){
                if ((pas+r)<=N && v[pas+r]<x)
                    r+=pas;
                pas/=2;
            }
        }

               p=p+N-r;


    }
    out<<  p << endl;

    out.close ();
    in.close ();
    return 0;
}