program random(input,output);
var
 a:array [1..1010] of longint;
 n,m,i,j,fu,x:longint;
procedure pai(head,tail:longint);
var
 i,k,l,o:longint;
begin
 i:=head;
 l:=tail;
 k:=a[(head+tail) div 2];
   repeat
   while a[i]<k do i:=i+1;
    while a[l]>k do l:=l-1;
     if i<=l then
      begin
       o:=a[i];
       a[i]:=a[l];
       a[l]:=o;
       i:=i+1;
       l:=l-1;
      end;
     until i>l;
   if i<tail then pai(i,tail);
   if head<l then pai(head,l);
  end;

begin
 assign(input,'random.in');
 assign(output,'random.out');
 reset(input);
 rewrite(output);
 readln(n);
 for i:=1 to n do read(a[i]);
 fu:=n;
  pai(1,n);
  x:=a[n];

 for i:=1 to n do begin
  if
  (a[i]=a[i+1]) and (i<=fu)
     then begin
    a[i]:=0;
     fu:=fu-1;
     for j:=i to n do
      a[j]:=a[j+1];
      end;
     end;
     writeln(fu);
  for i:=1 to fu do
   write(a[i],' ');
  close(input);
  close(output);
  end.