{$IFDEF NORMAL}
  {$H-,I+,OBJECTCHECKS-,Q-,R-,S-}
{$ENDIF NORMAL}
{$IFDEF DEBUG}
  {$H-,I+,OBJECTCHECKS-,Q+,R-,S-}
{$ENDIF DEBUG}
{$IFDEF RELEASE}
  {$H-,I-,OBJECTCHECKS-,Q-,R-,S-}
{$ENDIF RELEASE}
program   economie;
type   vector=array[1..100000] of byte;
var       n,p,i,j:longint;
          v,baza:vector;
          f:text;




begin
assign(f,'economie.in'); reset(f); readln(f,n);fillchar(v,sizeof(v),0);
for i:=1 to n do
       begin
       read(f,p);
       v[p]:=1;
       end;
close(f);
i:=1;
while i<=50000 do
begin
while v[i]<>1 do inc(i); p:=0; inc(p);
baza[p]:=i; {if 2*i<=50000 then }v[2*i]:=2 ;n:=i+1;
while n<=50000-i do
        begin
        if v[n]=2 then v[n+i]:=2;
        n:=n+1;
        end;
i:=i+1;
end;
assign(f,'economie.out'); rewrite(f); writeln(f,p);
for i:=1 to p do writeln(f,baza[i]);
close(f);
















end.