const
  n = 3;
  a: array[1 .. n, 1 .. n] of integer =
    ((1, 2, 3),
     (4, 5, 6),
     (7, 8, 9));

var
  steps: array[1 .. 2*n - 1] of byte;

var
  i, j, ii, jj: integer;

begin
  j := 0;
  for i := 2*n-1 downto 1 do begin
    if odd(i) then inc(j);
    steps[i] := j
  end;

  j := 0;
  ii := 1; jj := 0;
  repeat

    if j < 2*n-1 then begin
      inc(j);
      for i := 1 to steps[j] do begin
        inc(jj); write(a[ii, jj]:5);
      end;
    end;

    if j < 2*n-1 then begin
      inc(j);
      for i := 1 to steps[j] do begin
        inc(ii); write(a[ii, jj]:5);
      end;
    end;

    if j < 2*n-1 then begin
      inc(j);
      for i := 1 to steps[j] do begin
        dec(jj); write(a[ii, jj]:5);
      end;
    end;

    if j < 2*n-1 then begin
      inc(j);
      for i := 1 to steps[j] do begin
        dec(ii); write(a[ii, jj]:5);
      end;
    end;

  until j = (2*n - 1);
  writeln;

end.