#include <fstream>
#define mx(a, b) ((a > b) ? a : b)
using namespace std;
int a[1025][1025], li[1025], ci[1025], subs[1025],kl,m,n;
int main()
{int i,j;
ifstream in("cmlsc.in");
ofstream o("cmlsc.out");
in>>n>>m;
for(i=1;i<=n;++i)
    in>>li[i];
for(i=1;i<=m;++i)
    in>>ci[i];
for(i=1;i<=n;++i)
for(j=1;j<=m;++j)
if(li[i]==ci[j]) a[i][j]=a[i-1][j-1]+1;
else  a[i][j] = mx(a[i-1][j], a[i][j-1]);

for(i=n,j=m;i;)
if(li[i]==ci[j]) subs[++kl]=li[i], --j, --i;
else if(a[i-1][j]<a[i][j-1]) --j;
     else --i;

o<<kl<<'\n';
for(i=kl;i;--i)
    o<<subs[i]<<" ";
    o.close();
    return 0;
}