#include <iostream>
#include <fstream>
using namespace std;
ifstream f("nrtri.in");
ofstream g("nrtri.out");
int n,i,v[30001],ok,aux,a,b,c,nrtr,c3,c2;
int main()
{
    f>>n;
    for(i=1; i<=n; i++)
    {
        f>>v[i];
    }
    do
    {
        ok=1;
        for(i=1; i<n; i++)
            if(v[i]>v[i+1])
            {
                ok=0;
                aux=v[i];
                v[i]=v[i+1];
                v[i+1]=aux;
            }
    }
    while(ok!=1);
    for(i=1; i<=n; i++)
        while(n!=0)
        {
            c3=n;
            c2=n-1;
            a=v[n];
            for(b=v[c3-1]; c3>=1; c3--)
            {
                b=v[c3-1];
                for(c=v[c2-1]; c2>=1; c2--)
                {
                    c=v[c2-1];

                    if(c+b>=a)
                        nrtr++;
                }
            }
            n--;
        }
    g<<nrtr;
    return 0;
}