program dsa;
const fi='cmlsc.in';
      fo='cmlsc.out';
var f,g:text;
    d:array[0..1024,0..1024] of integer;
    sir,v,x:array[0..1024] of integer;
    n,i,j,m,bst,i1:integer;
begin
   assign(f,fi);reset(f);
   assign(g,fo);rewrite(g);
   read(f,n,m);
   for i:=1 to n do
      read(f,v[i]);
   for j:=1 to m do
      read(f,x[j]);

  for i:=1 to n do
   for j:=1 to m do
     if v[i]=x[j] then
          d[i,j]:=1+d[i-1,j-1]
     else
        begin
          if d[i-1,j]>d[i,j-1] then
            d[i,j]:=d[i-1,j]
           else
             d[i,j]:=d[i,j-1];
        end;
   writeln(g,d[n,m]);

   i:=n; j:=m;
   for i1:=d[n,m] downto 1 do
     begin
       while d[i, j]=d[i,j-1] do
         dec(j);
       while d[i, j]=d[i-1,j] do
        dec(i);
      sir[i1]:=v[i];
      dec(i);
     end;

   for i := 1 to d[n, m] do
      write(g,sir[i],' ');

   close(f);
   close(g);
end.