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