var a, b, rez:array[1..1024] of integer;
    v:array[0..1024, 0..1024] of integer;
    m, n, i, ii, j:integer;
    f, g: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);
  assign(g,'cmlsc.out'); rewrite(g);
    readln(f,m,n);
      for i:=1 to m do
        begin
          read(f,a[i]);
        end;
      for i:=1 to n do
        begin
          read(f,b[i]);
        end;
      for i:=1 to m do
        for j:=1 to n do
          begin
            if a[i]=b[j] then
              v[i,j]:=v[i-1,j-1]+1
              else
                 v[i,j]:=max(v[i-1,j], v[i,j-1]);
          end;
        writeln(g,v[m,n]);
      i:=m;
      j:=n;
         for ii:=v[m,n] downto 1 do
            begin
              While v[i,j]=v[i-1,j] do i:=i-1;
              while v[i,j]=v[i,j-1] do j:=j-1;
              rez[ii]:=a[i];
              i:=i-1;
            end;
              for i:=1 to v[m,n] do
                write(g,rez[i],' ');
  close(f); close(g);
end.