#include <iostream>
#include <algorithm>
#include <cstdio>

using namespace std;

int main()
{
    freopen("nrtri.in","r",stdin);
    freopen("nrtri.out","w",stdout);
    int n,v[801],i,j,k,r=0;
    cin>>n;
    for(i=1; i<=n; i++)
        cin>>v[i];
    sort(v+1,v+n+1);
    for(i=1; i<=n; i++)
        for(j=i+1;j<=n;j++)
            for(k=j+1;k<=n;k++)
                if(v[i]+v[j]>=v[k])
                    r++;
    cout<<r;
    return 0;
}