#include <fstream>

using namespace std;

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

int n,m,i,j,a[1030],b[1030],d[1030][1030],sol[1030],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]);
    i = n;
    j = m;
    while (i >= 1 && j >= 1)
    {
        if (a[i] == b[j])
        {
            sol[++k] = a[i];
            i--;
            j--;
        }
        else
            if (d[i-1][j] > d[i][j-1])
                i--;
            else
                j--;
    }
    fout << k << "\n";
    for (i=k; i>=1; i--)
        fout << sol[i] << " ";
    return 0;
}