#include <bits/stdc++.h>

using namespace std;
ifstream f ("cmlsc.in");
ofstream g ("cmlsc.out");
#define maxim(a, b) ((a > b) ? a : b)
int m,n,a[1025],b[1025],d[1025][1025],sir[1025],bst;
int main()
{
    int i,j;
    f>>m>>n;
    for (i=1;i<=m;i++)
         f>>a[i];
    for (i=1;i<=n;i++)
         f>>b[i];
    for (i=1;i<=m;i++)
         for (j=1;j<=n;j++)
            {
               if(a[i]==b[j])
                  d[i][j]=1+d[i-1][j-1];
               else
                  d[i][j]=maxim(d[i-1][j],d[i][j-1]);
            }
     for (i=m,j=n;i;)
        {
         if (a[i]==b[j])
            {
             sir[++bst]=a[i];
             i--;
             j--;
            }
        else
            if (d[i-1][j]<d[i][j-1])
                j--;
        else
            i--;
        }
    g<<bst<<'\n';
    for(i=bst;i;i--)
        g<<sir[i]<<" ";
    return 0;
}