uses crt;
var n,i,d: integer;
    a,b: array[1..10000] of integer;
function dempt(d: integer): integer;
var i: integer;
begin
    dempt:=0;
    for i:=1 to n do if d=a[i] then inc(dempt);
end;
begin
clrscr;
    readln(n);
    d:=0;
    for i:=1 to n do read(a[i]);
    for i:=1 to n do if dempt(a[i])=1 then begin
        inc(d);
        b[d]:=a[i];
    end;
    writeln(d);
    for i:=1 to d do write(b[i],' ');
    readln
end.

uses crt;
var A, B : array [1 .. 1000] of integer;
    i, N, j, x : integer;

function KK (z : integer) : integer;
begin
    KK := 0; j := 1;
    while (j <= N) and (KK <= 1) do
        begin
            if z = A[j] then KK := KK + 1;
            j := j + 1;
        end;
end;

begin
clrscr;
readln(N);
for i := 1 to N do read(A[i]);

x := 0;
for i := 1 to N do
    if KK (A[i]) = 1 then
        begin
            x := x + 1;
            B[x] := A[i];
        end;

writeln(x);
for i := 1 to x do write(B[i],' ');

readln
end.