program u1014;

var
  n,u :longint;
  so :string;

begin
  readln(n);
  if n=0 then begin
    writeln('10');
    halt;
  end;
  so:='';
  u:=9;
  while n>9 do begin
    while (n mod u<>0) and (u>1) do dec(u);
    if u=1 then begin
      writeln('?');
      halt;
    end;
    so:=chr(48+u)+so;
    n:=n div u;
  end;
  so:=chr(48+n)+so;
  writeln(so);
end.

> program u1014;
>
> var
>   n,u :longint;
>   so :string;
>
> begin
>   readln(n);
>   if n=0 then begin
>     writeln('10');
>     halt;
>   end;
>   so:='';
>   u:=9;
>   while n>9 do begin
>     while (n mod u<>0) and (u>1) do dec(u);
>     if u=1 then begin
>       writeln('?');
>       halt;
>     end;
>     so:=chr(48+u)+so;
>     n:=n div u;
>   end;
>   so:=chr(48+n)+so;
>   writeln(so);
> end.
>

W.A. Because in thy algorithm instead of "?" It is necessary to
remove "-1"
If that write on Zintel@inbox.ru