program bing;
var
 f1,f2:text;
 n,m:integer;
 a:array[0..1000] of integer;
 i,j,k:integer;
begin
 assign(f1,'random.in');reset(f1);
 assign(f2,'random.out');rewrite(f2);
 readln(f1,n);
 m:=n;
 for i:=1 to n do
 read(f1,a[i]);
 for i:=1 to n-1 do
  for j:=i+1 to n do
   if a[j]<=a[i] then begin
   k:=a[j];a[j]:=a[i];a[i]:=k;
   end;
 for i:=2 to n do
 if a[i]=a[i-1] then m:=m-1;
 writeln(f2,m);
 write(f2,a[1],' ');
 for i:=2 to n do
  if a[i]<>a[i-1] then write(f2,a[i],' ');
 close(f1);close(f2);
end.