program random;
var
  i,j,tmp,n:integer;
  a:array [0..100] of integer;
  flag:boolean;
begin
  fillchar (a,sizeof(a),0);
  assign (input,'random.in');
  reset (input);
  readln (n);
  for i:=1 to n do begin
    read (tmp);flag:=true;
    for j:=1 to i-1 do if tmp=a[i] then flag:=false;
    if flag then begin
      a[i]:=tmp;
      inc(a[0]);
    end;
  end;
  close (input);
  assign (output,'random.out');
  rewrite (output);
  writeln (a[0]);
  for i:=1 to a[0]-1 do for j:=i+1 to a[0] do if a[i]>a[j] then begin
    tmp:=a[i];
    a[i]:=a[j];
    a[j]:=tmp;
  end;
  for i:=1 to a[0] do write (a[i],' ');
  close (output);
end.