var  i,j,m1,n:integer;
     a,b:array[1..1050] of integer;
     m:array[0..1050,0..1050] of integer;
     f,g:text;
procedure drum(i,j:integer);
begin
   if (i<>0) and (j<>0) then
     if a[i]=b[j] then begin
        drum(i-1,j-1);
        write(g,a[i],' ');
     end else
         if m[i-1,j]>m[i,j-1] then drum(i-1,j)
            else drum(i,j-1);
end;
begin
assign(f,'cmlsc.in');reset(f);
assign(g,'cmlsc.out');rewrite(g);
read(f,n,m1);
for i:=1 to n do
    read(f,a[i]);
for j:=1 to m1 do
    read(f,b[j]);
for i:=1 to n do
    for j:=1 to m1 do
        if a[i]=b[j] then  m[i,j]:=m[i-1,j-1]+1
           else if m[i-1,j]>m[i,j-1] then  m[i,j]:=m[i-1,j]
                   else m[i,j]:=m[i,j-1];
i:=n;j:=n;
writeln(g,m[n,m1]);
drum(n,m1);
close(g);
end.