program asdf;
type
    mat=array[0..1024,0..1024] of integer;
    vect=array[1..1024] of integer;

var
    ma:mat;
    i,j,k,n,m:integer;
    v1,v2,z:vect;
    f,g:text;

begin
    assign(f,'cmlsc.in');reset(f);
    readln(f,n,m);
    for i:=1 to n do read(f,v1[i]);
    for i:=1 to m do read(f,v2[i]);
    for i:=1 to n do
        for j:=1 to m do
            if (v1[i]=v2[j]) then ma[i,j]:=ma[i-1,j-1]+1
            else if (ma[i-1,j]<ma[i,j-1]) then ma[i,j]:=ma[i,j-1]
                                        else ma[i,j]:=ma[i-1,j];

    close(f);
    i:=n;j:=m;
    k:=0;

    while (i>=1) and (j>=1) do
        begin
        if v1[i]=v2[j] then
            begin
            k:=k+1;
            z[k]:=v1[i];
            i:=i-1;
            j:=j-1;
            end
        else if ma[i-1,j]>ma[i,j-1] then i:=i-1
                                    else j:=j-1;
        end;
    assign(g,'cmlsc.out');rewrite(G);
    writeln(g,k);
    for i:=k downto 1 do
        write(g,z[i],' ');
    close(g);
end.