Var
     db:longint;
     i,j,a,b,c,k:word;
     n:word;
     et,v:array[-1..801] of 0..30000;
     f:text;
     kesz,jo:boolean;
Function szetvalogat(e,u:word):word;
var seged:integer;
begin
  seged:=et[e];
  while e<u do begin
    while (e<u) and (et[u]>=seged) do
      dec(u);
    if e<u then begin
      et[e]:=et[u];
      inc(e);
      while (e<u) and (et[e]<seged) do
        inc(e);
      et[u]:=et[e];
      dec(u);
    end;
  end;
  et[e]:=seged;
  szetvalogat:=e;
end;
procedure gyors(ah,fh:integer);
var k:integer;
begin
  if ah<fh then begin
    k:=szetvalogat(ah,fh);
    gyors(ah,k-1);
    gyors(k+1,fh);
  end;
end;
{function binker(e,u:integer):integer;
var k:integer;
begin
  if e>u then binker:=0
  else begin
    k:=(e+u) div 2;
    if (et[k]<=a+b) and then binker:=k
    else
      if mit<et[k] then binker:=binker(e,k-1,mit)
      else binker:=binker(k+1,u,mit);
  end;
end;               }

begin
Assign(f,'nrtri.in');
reset(f);
readln(f,n);
for i:=1 to n do
 read(f,et[i]);
close(f);
gyors(1,n);
i:=n;
k:=n;
while k>1 do begin
i:=k;
while i>3 do begin
  jo:=true;
  a:=et[k];
  b:=et[i];
  j:=i-1;
  while (jo) and (j>0) do begin
    c:=et[j];
    if (c>a+b) or (a>c+b) or (b>c+a) then jo:=false;
    j:=j-1;
  end;
  db:=db+i-j-2;
  i:=i-1;
end;
k:=k-1;
end;

writeln(db);
assign(f,'nrtri.out');
rewrite(f);
end.