#include <fstream>
#include <algorithm>
using namespace std;
ifstream f("cmlsc.in");
ofstream g("cmlsc.out");
short m,n,i,j,a[1025],b[1025],c[1025],d[1025][1025];
int main()
{
   f>>n>>m;
   for(i=1;i<=n;i++)
    f>>a[i];
   for(i=1;i<=m;i++)
    f>>b[i];
   for(i=1;i<=n;i++)
    for(j=1;j<=m;j++)
      if(a[i]==b[j])
                d[i][j]=d[i-1][j-1]+1;
            else
                d[i][j]=max(d[i-1][j],d[i][j-1]);
    i=n;
    j=m;
    c[0]=0;
    while(i)
        if(a[i]==b[j])
        {
            c[0]++;
            c[c[0]]=a[i];
            i--;
            j--;
        }
        else
            if(d[i-1][j]<d[i][j-1])
                j--;
            else
                i--;
    g<<c[0]<<"\n";
    for(i=c[0];i>=1;i--)
       g<<c[i]<<" ";
    return 0;
}