type matrix=array[1..1024,1..1024] of integer;
     vek=array[1..1024] of integer;
var x:matrix;
    v1,v2,v3:vek;
    i,j,n,m,k,p:integer;
    f:text;
function max(a,b:integer):integer;
 var i,j,d:integer;
  begin
   d:=0;
   for i:= 1 to a do
    for j:= 1 to b do
     if d<x[i,j] then d:=x[i,j];
   max:=d;
  end;
begin
 assign(f,'cmlsc.in');
 reset(f);
 readln(f,n,m);
 for i:= 1 to n do
  read(f,v1[i]);
 readln(f);
 for i:= 1 to m do
  read(f,v2[i]);
 close(f);
 k:=0;
 for i:= 1 to n do
  for j:= 1 to m do
   if v1[i]=v2[j] then x[i,j]:=max(i-1,j-1)+1;
 k:=max(n,m);
 p:=1;
 for i:= n downto 1 do
   for j:= 1 to m do
     if (x[i,j]=k) and (x[i,j]<>0) then begin
                                         v3[p]:=v1[i];
                                         inc(p); dec(k);
                                         end;
 assign(f,'cmlsc.out');
 rewrite(f);
 writeln(f,max(n,m));
 for i:= 1 to p-1 do
  write(f,v3[i],' ');
 close(f);
end.