program romanfel;
uses crt;
type vektor = array [1..1024] of integer;
     matrix = array [0..1024,0..1024] of integer;
var x:matrix;
  v,v1,v2:vektor;
  i,j,n,m,b,k:integer;
  f,g:text;
procedure beolvas(var v,v1:vektor; var n,m:integer);
 var i:integer;
 begin
  assign (f,'cmlsc.in');
  reset (f);
  read (f,m,n);
  readln(f);
  for i:= 1 to m do
   read (f,v[i]);
  readln(f);
  for i:= 1 to n do
   read(f,v1[i]);
 end;
begin
 clrscr;
 beolvas(v,v1,n,m);
 for i:= 1 to n do
  x[0,i]:=0;
 for i := 1 to m do
  x[i,0] := 0;
 for i := 1 to m do
  begin
   for j := 1 to n do
    begin
     if v[i] = v1[j] then x[i,j] := x[i-1,j-1] + 1
                    else if x[i,j-1] > x[i-1,j] then x[i,j] := x[i,j-1]
                                                else x[i,j] := x[i-1,j];
    end;
  end;
 i:=m;
 j:=n;
 for k := 1 to x[m,n] do
  begin
   while x[i,j-1]=x[i,j] do
    dec(j);
   while x[i-1,j]=x[i,j] do
    dec(i);
   v2[k] := v[i];
   dec(i);
   dec(j);
  end;
 assign(g,'cmlsc.out');
 rewrite(g);
 write(g,x[m,n]);
 writeln(g);
 for i := x[m,n] downto 1 do
  write (g,v2[i],' ');
 close(g);

end.