[PhoeniX]

Так пойдёт?

Код:

  writeln('vvedite nomer dnya ne visokosnogo goda');
  readln(k);
  if (k>=1) and (k<=365) then begin
    m:=jan;
    d:=1;
    while k>0 do begin
      if m=feb then d:=28
      else if m in [jan, mar, may, jul, aug, oct, dec] then d:=31
      else d:=30;
      if k>d then begin
        inc(m);
        k:=k-d;
      end else begin
        d:=k; break;
      end;
    end;
    case m of
      jan:writeln('January');
      feb:writeln('February');
      .....