#include<fstream.h>
long int n,i,j,k,v[100];
int main ()
{
ifstream in("nrtri.in");
ofstream out("nrtri.out");
in>>n;
for (i=1;i<=n;i++)
in>>v[i];
for (i=1;i<=n;i++)
{ for (j=1;j<=n;j++)
  { for (k=1;k<=n;k++)
    if((v[i]+v[j]>=v[k])&&(v[i]+v[k]>=v[j])&&(v[j]+v[k]>=v[i])){ k++;}}  }
out<<k;
return 0;
}