#include <fstream>
using namespace std;

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

int dp[1025][1025];
//dp[i][j] = lungimea celui mai lung subsir comun al secventelor (prefixelor) a[1...i], b[1...j]
int sol[1025];

int main()
{
    int i, j, n, m, a[1025], b[1025];
    fin >> n >> m;
    for (i = 1; i<=n; i++)
        fin >> i[a];
    for (i = 1; i<=m; i++)
        fin >> i[b];
    for (i = 1; i<=n; i++)
        for (j = 1; j<=m; 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]);
        }
    i = n;
    j = m;
    int k = 0;
    for (;i>0 && j>0;)
    {
        if (a[i] == b[j])
        {
            k++;
            sol[k] = a[i];
            i--;
            j--;
        }
        else if (dp[i-1][j] > dp[i][j-1])
            i--;
        else
            j--;
    }
    fout << dp[n][m] << '\n';
    for (i = k; i>=1; i--)
        fout << i[sol] << ' ';
    return 0;
}