#include <iostream>
#include <fstream>
using namespace std;
ifstream f ("nrtri.in");
ofstream g ("nrtri.out");
int v[800];
int main()
{
    int n,i,cont,j,k;
    f>>n;
    for (i=1;i<=n;++i)
        f>>v[i];
    cont=0;
    for (i=1;i<=n-2;++i)
    {
        for (j=i+1;j<=n-1;++j)
        {
            for (k=i+2;k<=n;++k)
            {
                if (v[i]+v[j]>v[k] && v[j]+v[k]>v[i] && v[i]+v[k]>v[j])
                    ++cont;
            }
        }
    }
    g<<cont;
    return 0;
}