program cel_mai_lung_subsir_comun;
var a,b:array[1..1024] of byte;
l:array[0..1024,0..1024] of integer;
f,g:text;
sol:array[1..1024] of integer;
n,m,i,k,x,y:integer;

begin
assign(f,'cmlsc.in');reset(f);
assign(g,'cmlsc.out');rewrite(g);

readln(f,n,m);

for i:=1 to n do
read(f,a[i]);
readln(f);

for i:=1 to m do
read(f,b[i]);
close(F);

for x:=1 to n do
for y:=1 to m do
if a[x]=b[y] then
l[x,y]:=l[x-1,y-1]+1
else
if l[x-1,y]>l[x,y-1] then
l[x,y]:=l[x-1,y]
else
l[x,y]:=l[x,y-1];

writeln(g,l[n,m]);
k:=l[n,m];

x:=n;y:=m;
while k>0 do
if a[x]=b[y] then
begin
sol[k]:=a[x];
k:=k-1;
x:=x-1;
y:=y-1;
end
else
if l[x,y]=l[x,y-1] then y:=y-1
else x:=x-1;

for i:=1 to l[n,m] do
write(g,sol[i],' ');
close(g);
end.