type vector=array[1..1024] of integer;
var f,g:text;
i,j,a,b:integer;
c,q:array[0..1024,0..1024] of 0..1025;
x,y:array[1..1024] of integer;
procedure lungimecmlsc(x,y:vector);
var i,j:integer;
begin
        for i:=1 to a do
                c[i,0]:=0;
        for j:=0 to b do
                c[0,j]:=0;
        for i:=1 to a do
                for j:=1 to b do
                        if x[i]=y[j] then begin
                                c[i,j]:=c[i-1,j-1]+1;q[i,j]:=1;end
                        else
                                if c[i-1,j]>=c[i,j-1] then begin
                                        c[i,j]:=c[i-1,j];
                                        q[i,j]:=2;end
                                else               begin
                                        c[i,j]:=c[i,j-1];
                                        q[i,j]:=3;end;
end;
procedure scrie(i,j:integer);
begin
        if (i>0) and (j>0) then begin
        if q[i,j]=1 then begin
                scrie(i-1,j-1);
                write(g,x[i],' ');end
        else
                if q[i,j]=2 then
                        scrie (i-1,j)
                else
                        scrie (i,j-1); end;
end;
begin
        assign(f,'cmlsc.in');assign(g,'cmlsc.out');
        reset(f);rewrite(g);
        read(f,a,b);
        for i:=1 to a do
                read (f,x[i]);
        for i:=1 to b do
                read (f,y[i]);
        lungimecmlsc(x,y);
        writeln (g,c[a,b]);
        scrie(a,b);
        close(f);close(g);

end.