#include<iostream>
#include<fstream>
#include<algorithm>
using namespace std;
ifstream in("nrtri.in");
ofstream out("nrtri.out");
int n;
int v[801];
int main()
{
    in>>n;
    for(int i=0;i<n;i++)
        in>>v[i];
    sort(v,v+n);
    int zz=0,i,j,k;
    for( i=0;i<=n-3;i++)
        for( j=i+1;j<=n-2;j++)
    {
        for( k=j+1;k<n;k++)
            if(v[i]+v[j]>=v[k] and v[j]+v[k]>=v[i] and v[i]+v[k]>=v[j])
                 zz++;
    }
    out<<zz;
}