#include <fstream>
using namespace std;
ifstream cin("nrtri.in");
ofstream cout("nrtri.out");
int n, i, a[802], c, j, k;
int main()
{
    cin>>n;
    for(i=1;i<=n;++i)
        cin>>a[i];
    c=0;
    for(i=1;i<=n;++i)
        for(j=i+1;j<=n;++j)
            for(k=j+1;k<=n;++k)
                if(a[i]+a[j]>=a[k] and a[j]+a[k]>=a[i] and a[k]+a[i]>=a[j]) c++;
    cout<<c<<'\n';
    return 0;
}