#include <iostream>
#include <fstream>
using namespace std;

ifstream f("nrtri.in");
ofstream g("nrtri.out");
int main()
{
    int n; f>>n;
    int v[n];
    for(int i=1;i<=n;i++)
        f>>v[i];

    int tr=0;
    for(int a=1;a<=n-2;a++)
    for(int b=a+1;b<=n-1;b++)
    for(int c=b+1;c<=n;c++)
    if (v[a]<=v[b]+v[c] && v[b]<=v[a]+v[c] && v[c]<=v[a]+v[b])
        tr++;
    g<<tr;
}