var n,m,z,i,j : longint;
    a,b,v : array[0..1025] of integer;
    c : array[0..1025,0..1025] of integer;
    f,g : text;
function maxim(x,y : longint):longint;
begin
  if x>y then maxim:=x
  else maxim:=y;
end;
begin
assign(f,'cmlsc.in');reset(f);
assign(g,'cmlsc.out');rewrite(g);
read(f,n,m);
for i:=1 to n do read(f,a[i]);
for j:=1 to m do read(f,b[j]);
for i:=1 to n do
  for j:=1 to m do
    if a[i]=b[j] then
      c[i,j]:=c[i-1,j-1]+1
    else
      if c[i-1,j]>c[i,j-1] then
        c[i,j]:=c[i-1,j]
      else
        c[i,j]:=c[i,j-1];

writeln(g,c[n,m]);
i:=n; j:=m;
repeat
  if a[i]=b[j] then
  begin
    inc(z);v[z]:=a[i];
    dec(i);dec(j);dec(c[n,m]);
  end
  else
    if c[i-1,j]>c[i,j-1]then
      dec(i)
    else
      dec(j);
until (i<=0)or(j<=0)or(c[n,m]=0);
for i:=z downto 1 do write(g,v[i],' ');
writeln(g);
close(g);
end.