program razy;
var a:array[1..100] of integer;
    nr,j,k,n,i,aux:integer;
    f,g:text;
begin
assign(f,'nrtri.in');reset(F);
assign(g,'nrtri.out');rewrite(g);
readln(f,n);
for i:=1 to n do
  read(f,a[i]);
for i:=1 to n-1 do
  for j:=i+1 to n do
    if a[i]>a[j] then begin
                      aux:=a[i];
                      a[i]:=a[j];
                      a[j]:=aux;
                      end;
nr:=0;
for i:=1 to n-2 do
  for j:=i+1 to n-1 do
    for k:=j+1 to n do
      if (a[i]+a[j]>=a[k]) and (a[i]+a[k]>=a[j]) and (a[k]+a[j]>=a[i]) then nr:=nr+1;
writeln(g,nr);
close(f);close(g);
end.