#include <fstream>

using namespace std;

int d[1030][1030], a[1030], b[1030];
int n, m, i, j;

ifstream fin ("cmlsc.in");
ofstream fout("cmlsc.out");

void drum(int i, int j, int k)
{
    if (k!=0)
    {
        if (a[i] == b[j])
        {
            drum(i-1, j-1, k-1);
            fout<<a[i]<<" ";
        }
        else if (d[i-1][j] > d[i][j-1])
            drum(i-1, j, k);
        else
            drum(i, j-1, 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] = 1 + d[i-1][j-1];
            }
            else
            {
                d[i][j] = max(d[i-1][j], d[i][j-1]);
            }

    fout<<d[n][m]<<"\n";
    drum(n, m, d[n][m]);
    return 0;
}