var fi,fo:text;
    n:integer;
procedure switch;
var i:integer;
begin
  writeln(fo,n,' ',n+1);
  for i:=n downto 2 do
    writeln(fo,i-1,' ',i);
  writeln(fo,n+1,' ',1);
end;
procedure rotate(poz,ct:integer);
var i:integer;
begin
  for i:=1 to n-ct do
    writeln(fo,poz,' ',n+1);
  for i:=1 to n-ct do
    writeln(fo,n+1,' ',poz);
end;
var i,ct:integer;
begin
  assign(fi,'tije.in'); reset(fi);
  assign(fo,'tije.out'); rewrite(fo);
  read(fi,n);
  ct:=1;
  while ct<n do
   begin
    switch;
    if ct<n-1 then
    for i:=1 to n do
     rotate(i,ct);
    inc(ct);
   end;
  close(fi);
  close(fo);
end.