#include <iostream>
#include <fstream>

using namespace std;

ifstream fin("nrtri.in");
ofstream fout("nrtri.out");

int n, v[30005], cnt;

int triunghi(int a, int b, int c)
{
    if( a + b >= c && a + c >= b && b + c >= a)
        return 1;
    return 0;
}
int main()
{
    fin>>n;
    for(int i = 1; i <= n; i++)
        fin>>v[i];
    for(int i = 1; i <= n - 2 ; i++)
        for(int j = i + 1; j <= n-1; j++)
            for(int k = j + 1; k <= n; k++)
                if(triunghi(v[i], v[j], v[k]))
                    cnt++;
    fout<<cnt;


return 0;
}