#include<fstream> 
 #include<algorithm>
  using namespace std;   int v[999],n,i,q,k,j;  int main()   {           ifstream fin("nrtri.in");      fin>>n;        for(i=1;i<=n;i++)          fin>>v[i];         sort(v+1,v+n+1);         for(i=1;i<n-1;i++)          for(j=i+1;j<n;j++)              for(k=j+1;k<=n;k++)                  if(v[i]+v[j]>=v[k])                      q++;                  else break;         ofstream fout("nrtri.out");       fout<<q;  return 0;  }