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