program p1316;
var a:array[1..1000] of boolean;s:array[1..100] of longint;
i,n:longint;
begin
readln(n);fillchar(a,sizeof(a),false);
for i:=1 to n do
begin
read(s[i]);
a[s[i]]:=true;
end;
writeln(n);
for i:=1 to 1000 do
begin
if a[i] then write(i);
end;
end.