#include <fstream>
#include <algorithm>
using namespace std;
ifstream fin ("cmlsc.in");
ofstream fout ("cmlsc.out");

int d[1025][1025],a[1025],b[1025],sol[1025];
int n,m,i,j,k;

int main () {

    fin>>n>>m;
    for (i=1;i<=n;i++)
        fin>>a[i];
    for (i=1;i<=m;i++)
        fin>>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]);
        }

    fout <<d[n][m]<<"\n";

    i=n;j=m;

    while (k!=d[n][m]) {
        if (a[i]==b[j]) {
            sol[++k]=a[i];
            i--;
            j--;
        }else
            if(d[i-1][j]<d[i][j-1])
                j--;
            else
                i--;
    }

    for (i=k;i>=1;i--)
        fout<<sol[i]<<" ";
    return 0;
}