var i,j,n,k:longint;
    f,g:text;
begin
 assign(f,'tije.in'); reset(f);
 assign(g,'tije.out'); rewrite(g);
 read(f,n);
 for i:=n-1 downto 1 do begin
  for j:=n downto 1 do
   for k:=1 to i div 2 do begin
    writeln(g,j,' ',j+1);
    writeln(g,j,' ',j+1);
   end; 
   if i mod 2=1 then
    writeln(g,j,' ',j+1);
  for k:=1 to i div 2 do begin
   writeln(g,n+1,' ',1);
   writeln(g,n+1,' ',1);
  end;
  if i mod 2=1 then
   writeln(g,n+1,' ',1);  
 end;
 close(f); close(g);
end.