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-1 downto 1 do begin
   for j:=n downto 1 do
      for k:=1 to i do
         writeln(g,j,' ',j+1);
   for k:=1 to i do
      writeln(g,n+1,' ',1);
   end;
close(f);
close(g);
end.