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

using namespace std;

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

int v[30001],n;
const int N=1<<10;

int caut(int x)
{
    int pas=N,r=0;
    while(pas!=0)
    {
        if(pas+r<=n && v[pas+r]<=x)
            r+=pas;
        pas/=2;
    }
        cout<<r<<" ";
        return r;
}

int main()
{
    int j,i,c=0,k;
    in>>n;
    for(i=1; i<=n; i++)
        in>>v[i];
    sort(v+1,v+n+1);
    for(i=1; i<n; i++)
        for(j=i+1; j<=n; j++)
        {
            k=caut(v[i]+v[j]);
            if(k>j)
                c+=k-j;
        }
    out<<c;
    return 0;
}