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