program numarare_triunghiuri;
var f,g:text;
    v:array[1..800]of 0..30000;
    n,i,j,y,c:longint;
begin
assign(f,'nrtri.in');
assign(g,'nrtri.out');
reset(f);
rewrite(g);
read(f,n);
for i:=1 to n do read(f,v[i]);
for i:=1 to n do
  for j:=i+1 to n do
    for y:=j+1 to n do
      if (v[i]+v[j]>=v[y])and(v[i]+v[y]>=v[j])and(v[j]+v[y]>=v[i])then
        inc(c);
write(g,c);
close(f);
close(g);
end.