program p1014;
var
  a:array[1..32]of integer;
  n:longint;
  i,j,sign,temp:integer;
  flag:boolean;
begin
  readln(n);
  sign:=0;
  flag:=true;
  while (n>=10)and flag do
    begin
      flag:=false;
      for i:=9 downto 2 do
        if n mod i=0 then
          begin
            flag:=true;
            sign:=sign+1;
            a[sign]:=i;
            n:=n div i;
            break
          end
    end;
  if not flag then
    begin
      writeln('?');
      halt
    end;
  sign:=sign+1;
  a[sign]:=n;
  for i:=1 to sign-1 do
    for j:=i+1 to sign do
      if a[i]>a[j] then
        begin
          temp:=a[i];
          a[i]:=a[j];
          a[j]:=temp
        end;
  for i:=1 to sign do
    write(a[i]);
  writeln
end.

> program p1014;
> var
>   a:array[1..32]of integer;
>   n:longint;
>   i,j,sign,temp:integer;
>   flag:boolean;
> begin
>   readln(n);
>   sign:=0;
>   flag:=true;
>   while (n>=10)and flag do
>     begin
>       flag:=false;
>       for i:=9 downto 2 do
>         if n mod i=0 then
>           begin
>             flag:=true;
>             sign:=sign+1;
>             a[sign]:=i;
>             n:=n div i;
>             break
>           end
>     end;
>   if not flag then
>     begin
>       writeln('?');
>       halt
>     end;
>   sign:=sign+1;
>   a[sign]:=n;
>   for i:=1 to sign-1 do
>     for j:=i+1 to sign do
>       if a[i]>a[j] then
>         begin
>           temp:=a[i];
>           a[i]:=a[j];
>           a[j]:=temp
>         end;
>   for i:=1 to sign do
>     write(a[i]);
>   writeln
> end.
Your program should print to the output the only number Q. If such a
number does not exist print –1.
But it not all is one more test at N=0. Think!