Program cmlsc;
type matrice=array[0..1024,0..1024] of integer;
	tabel=array[1..1024] of integer;
	var d:matrice;
			t,a,b:tabel;
			f1,f2:text;
			n,m,l:integer;

Function maxim(a,b:integer):integer;
	begin
		if a>=b then
			maxim:=a else
				maxim:=b;
	end;

Procedure citiredate;
	var i:integer;
	begin
		readln(f1,n,m);
		for i:=1 to n do 
			read(f1,a[i]);
		readln(f1);
		for i:=1 to m do 
			read(f1,b[i]);
	end;

Procedure gasiresir;
	var i,j:integer;
	begin
		l:=0;
		i:=n; 
		j:=m;
		while (i<>0) and (n<>0) do 
			if a[i]=b[j] then
				begin
					l:=l+1;
					t[l]:=a[i];
					i:=i-1;
					j:=j-1;
				end else
					if (d[i,j-1]>d[i-1,j]) then
						j:=j-1 else
							i:=i-1;
	end;

Procedure afisare;
	var i:integer;
	begin
		writeln(f2,l);
		for i:=l downto 1 do 
			write(f2,t[i],' ');
	end;

Procedure main;
	var i,j:integer;
	begin
		citiredate;

		for i:=1 to n do 
			for j:=1 to m do 
				if a[i]=b[j] then
					d[i,j]:=1+d[i-1,j-1] else
						d[i,j]:=maxim(d[i-1,j],d[i,j-1]);

		gasiresir;
		afisare;
	end;

begin
	assign(f1,'cmlsc.in'); reset(f1);
	assign(f2,'cmlsc.out'); rewrite(f2);
	main;
	close(f1);
	close(f2);
end.