#include<fstream>
using namespace std;

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

int a[1026], b[1026], n, m, dp[1026][1026], nou[1026];

int main()
{
    int i, j, k = 0;
    in >> m >> n;
    for (i = 1; i <= m; i++)
        in >> a[i];
    for (i = 1; i <= n; i++)
        in >> b[i];
    dp[0][0] = 0;
    for (i = 1; i <= m; i++)
    {
        for (j = 1; j <= n; j++)
        {
            if (a[i] == b[j])
                dp[i][j] = 1 + dp[i - 1][j - 1];
            else
                dp[i][j] = max(dp[i - 1][j], dp[i][j - 1]);
        }
    }
    out << dp[m][n] << '\n';
    for (i = m, j = n; i > 0; )
    {
        if (a[i] == b[j])
        {
            k++;
            nou[k] = a[i];
            i--;
            j--;
        }
        else
        {
            if (dp[i - 1][j] > dp[i][j - 1])
                i--;
            else
                j--;
        }
    }
    for (i = k; i >= 1; i--)
        out << nou[i] << " ";
    return 0;
}