program cmlsc;
type
tabel=array [0..1025,0..1025] of integer;
tab=array [0..1025] of integer;
var
t:tabel;
v,vv,v1:tab;
i,j,m,n,x:longint;
f1,f2:text;
function max(a,b:longint):longint;
begin
if a>b then max:=a else
max:=b;
end;
begin
assign (f1,'cmlsc.in');
assign (f2,'cmlsc.out');
reset (f1);
rewrite (f2);
readln (f1,n,m);
for i:=1 to n do read (f1,v[i]);
readln (f1);
for i:=1 to m do read (f1,vv[i]);
for i:=1 to n do
for j:=1 to m do begin
if v[i]=vv[i] then
t[i,j]:=t[i-1,j-1]+1 else
t[i,j]:=max(t[i-1,j],t[i,j-1]);
end;
i:=n;
j:=m;
while t[i,j]<>0 do begin
while (t[i-1,j]=t[i,j]) do i:=i-1;
while (t[i,j-1]=t[i,j]) do j:=j-1;
x:=x+1;
v1[x]:=v[i];
i:=i-1;
j:=j-1;
end;
writeln (f2,t[n,m]);
for i:=x downto 1 do
write (f2,v1[i],' ');
close (f1);
close (f2);
end.