#include <fstream>

using namespace std;

short D[1025][1025], n, m, i, j, v1[1024], v2[1024], sol[1024], idx;

int main()
{
    ifstream f("cmlsc.in");
    ofstream g("cmlsc.out");
    f >> n >> m;
    for (i=0;i<n;i++)
        f>>v1[i];
    for (i=0;i<m;i++)
        f>>v2[i];
    for (i=1;i<=n;i++)
        for (j=1;j<=m;j++)
            if (v1[i-1]==v2[j-1])
                D[i][j]+=(D[i-1][j-1]+1);
            else
                if (D[i-1][j] > D[i][j-1])
                    D[i][j] = D[i-1][j];
                else
                    D[i][j] = D[i][j-1];
    for (i=n, j=m; i;)
        if (v1[i-1] == v2[j-1])
            sol[idx++] = v1[i-1], --i, --j;
        else if (D[i-1][j] < D[i][j-1])
            --j;
        else
            --i;
    g << idx << '\n';
    for (i=idx-1;i>=0;--i)
        g << sol[i] << ' ';
    return 0;
}