// Arhiva Educationala - Cel mai lung subsir comun

var
    n, m, lst, i, j : longint;
    a, b : array [0..1024] of byte;
    sir  : array [1..1024] of integer;
    d    : array [0..1024, 0..1024] of integer;
    f : text;

function max (a, b: integer) : integer;
begin
if (a > b) then max := a else max := b;
end;


begin
assign  (f, 'cmlsc.in');
reset   (f);
readln  (f, n, m);
for i := 1 to n do
    read (f, a[i]);
readln  (f);
for i := 1  to m do
    read (f, b[i]);
close   (f);

for i := 1 to n do
    for j := 1 to m do
        if (a[i] = b[j]) then
            d[i,j] := d[i-1, j-1]  + 1
        else
            d[i,j] := max (d[i-1, j], d[i, j-1]);
i := n;
j := m;
while (i <> 0) and (j <> 0) do
    if (a[i] = b[j]) then
        begin
        inc (lst); sir [lst] := a[i];
        dec (i); dec (j);
        end
    else
    if (d[i-1,j] < d[i,j-1]) then
        dec (j)
    else
        dec (i);


assign  (f, 'cmlsc.out');
rewrite (f);
writeln (f, lst);
for i := lst downto 1 do
    write (f, sir[i], ' ');
writeln(f);
close   (f);
end.