#include <bits/stdc++.h>
using namespace std;
ifstream f("nrtri.in");
ofstream g("nrtri.out");
int n,v[801],nr=0,i,j,k;
int CautareBinara(int x)
{
    int Sol = -1, Left = 1, Right = n;
    while(Left <= Right)
    {
        int Mid = (Left+Right) / 2;
        if(v[Mid] == x)
        {
            Sol = Mid;
            break;
        }
        if(v[Mid] > x)
            Right = Mid - 1;
        if(v[Mid] < x)
            Left = Mid + 1;
    }
    return Sol;
}
int main()
{
    f>>n;
    for(i=1; i<=n; i++)
        f>>v[i];
    sort(v+1,v+n+1);
    for(i=1; i<=n; i++)
        for(j=i+1; j<=n; j++)
            for(k=j+1; k<=n; k++)
            {
                if(v[i]+v[j]>=v[k])
                    nr++;
            }
    g<<nr;
    f.close();
    g.close();
}