program random;
type
shuzu=array[1..1000] of integer;
var
s:shuzu;
i,j,m,n,x,y:integer;
f1,f2:text;
procedure qsort(l,r:Integer);
var
  i,j,x,y:integer;
begin
  i:=l; j:=r; x:=s[(l+r) DIV 2];
  repeat
    while s[i]<x do i:=i+1;
    while x<s[j] do j:=j-1;
    if i<=j then
    begin
      y:=s[i]; s[i]:=s[j]; s[j]:=y;
      i:=i+1; j:=j-1;
    end;
  until i>j;
  if l<j then qsort(l,j);
  if i<r then qsort(i,r);
end;
begin
assign(f1,'random.in');reset(f1);
assign(f2,'random.out');rewrite(f2);
readln(f1,n);
for i:=1 to n do
  read(f1,s[i]);
    qsort(1,n);
    i:=1;
  while i<=n do
   begin
   if s[i]=s[i+1] then
   begin
     for j:=i+1 to n do
     begin
        s[j]:=s[j+1];
        end;
        dec(n);
        end;
        inc(i);
     end;
     writeln(f2,n);
     for i:=1 to n do
     write(f2,s[i],' ');
     close(f2);
     end.