var v:array[1..2000000]of byte;
   n,i,j,k:longint;
begin
assign(input,'ciur.in');reset(input);
assign(output,'ciur.out');rewrite(output);
readln(n);
for i:=2 to trunc(sqrt(n)) do
  if v[i]=0 then
   for j:=2 to n div i do v[i*j]:=1;
for i:=n downto 2 do
  if v[i]=0 then begin
   inc(j);k:=i;
   if j=1000 then break;
  end;
  writeln(j);
 for i:=k to n do if v[i]=0 then write(i,' ');
 close(input);close(output);
end.