#include <fstream>
#include <iostream>
#include <algorithm>

using namespace std;
int main()
{
ifstream f("nrtri.in");
ofstream g("nrtri.out");


int n,v[805],i,j,k;
f>>n;
    for (int i=0; i<n; ++i)
        f>>v+i;
    long long nr=0;
    for ( i=0; i<n-2; ++i)
        for ( j=i+1; j<n-1; ++j)
            for( k=j+1; k<n; ++k)
                if (v[i]+v[j]>=v[k] && v[i]+v[k]>=v[j] && v[j]+v[k]>=v[i])
                    nr++;
    g<<nr;
return 0;
}