program cogs74;
const
   maxn=110;
var
   t,x,i,j,n:longint;
   a:array[1..maxn] of longint;
   f:array[1..1000] of boolean;
procedure kp(l,r:longint);
var
  i,j,x,t:longint;
begin
   i:=l; j:=r;
   x:=a[(l+r) div 2];
  repeat
    while a[i]<x do inc(i);
    while a[j]>x do dec(j);
     if i<=j then
       begin
         t:=a[i]; a[i]:=a[j]; a[j]:=t;
          inc(i); dec(j);
       end;
  until i>j ;
 if i<r then kp(i,r);
 if j>l then kp(l,j);
end;
begin
   assign(input,'random.in'); reset(input);
   assign(output,'random.out'); rewrite(output);
     readln(n);
     for i:=1 to 1000 do f[i]:=false;
     t:=0;
     for i:=1 to n do
      begin
       read(x);
       if not f[x] then
        begin
          inc(t);
          a[t]:=x;
          f[x]:=true;
        end;
      end;
     kp(1,t);
     writeln(t);
     for i:=1 to t-1 do write(a[i],' ');
     write(a[t]);
   close(input); close(output);
end.