type  mat=array[1..1024,1..1024] of integer;
      vek=array[1..1024] of integer;
var n,m,i,j,i1,j1,d,k,l,g,c,i2,j2:integer; f:text; a,b,q:vek; x:mat;
function max(r,t:integer):integer;
  var i,j,mx:integer;
  begin
    mx:=-1;
    for i:=1 to r do
      for j:=1 to t do
        if x[i,j]>mx then begin mx:=x[i,j]; if mx>0 then begin i1:=i;j1:=j;end
                else begin i1:=0; j1:=0;end; end;
    max:=mx;
  end;
begin
  assign(f,'cmlsc.in');
  reset(f);
  readln(f,m,n);
  for i:=1 to m do
    read(f,a[i]);
  readln(f);
  for i:=1 to n do
    read(f,b[i]);
  close(f); c:=0;
  for i:=1 to n do begin
    for j:=1 to m do
      if a[j]=b[i] then if (i>1) and (j>1) then begin
      x[i,j]:=max(i-1,j-1)+1;
      if x[i,j]>d then d:=x[i,j];
      end
      else begin
      x[i,j]:=1; d:=1;
      end;
    end;
  k:=n; l:=m; g:=0;
  repeat
    max(k,l);
    inc(g);
    if i1>0 then begin if g=1 then begin i2:=i1; j2:=j1; end;inc(c); q[c]:=a[j1];  end;
    k:=i1-1; l:=j1-1;
  until (k<=1) or (j<=1);
  assign(f,'cmlsc.out');
  rewrite(f);
  writeln(f,x[i2,j2]);
  for i:=c downto 1 do
  write(f,q[i],' ');
  close(f);
end.