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