太水了
var
a: array[1..1000] of Boolean;
i,b,c,n: Integer;
begin
read(n);
c:=n;
for i:=1 to n do
begin
read(b);
if a[b]=true then c:=c-1;
a[b]:=true;
end;
writeln(c);
for i:=1 to 1000 do if a[i] then write(i,' ');
end.