#include <fstream>
#include <algorithm>

using namespace std;

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

int n, m, nr, sol[1100], a[1100], b[1100], rez[1100][1100];

int main()
{
    int i, j;

    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])
                rez[i][j] = 1 + rez[i - 1][j - 1];
            else
                rez[i][j] = max(rez[i - 1][j], rez[i][j - 1]);
        }
    i = n; j = m;
    while (nr < rez[n][m])
    {
        if (a[i] == b[j])
        {
            sol[++nr] = a[i];
            i--;
            j--;
        }
        else if (rez[i - 1][j] > rez[i][j - 1])
            i--;
        else j--;
    }
    fout << rez[n][m] << '\n';
    for (i = nr; i >= 1; i--)
        fout << sol[i] << ' ';
    fout << '\n';
    return 0;
}