#include<fstream>
using namespace std;
ifstream f("nrtri.in");
ofstream g("nrtri.out");
int main()
{
    int s[801],i,j,k,n,c=0;
    f>>n;
    for(i=1;i<=n;i++)
    f>>s[i];
    sort(s+1,s+n+1);
    for(i=1;i<=n-2;i++)
       for(j=i+1;j<=n-1;j++)
          for(k=j+1;k<=n;k++)
             if(s[i]+s[j]>=s[k])// && s[i]+s[k]>=s[j] && s[k]+s[j]>s[i])
               c++;
    g<<c;
    return 0;
}