#include <fstream>
#define DMAX 1030
using namespace std;

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

int n, m;
int a[DMAX];
int b[DMAX];
int LCS[DMAX][DMAX];
char unde[DMAX][DMAX];

void citire();
void pd();
void afisare();

int main()
{
    citire();
    pd();
    afisare();
    return 0;
}
void citire()
{
    int i, j;
    fin >> n >> m;
    for (i = 1; i <= n; i++)
        fin >> a[i];
    for (i = 1; i <= m; i++)
        fin >> b[i];
}
void pd()
{
    int i, j;
    for (i = n; i > 0; i--)
        for (j = m; j > 0; j--)
            if (a[i] == b[j])
            {
                LCS[i][j] = 1 + LCS[i + 1][j + 1];
                unde[i][j] = '1';
            }
            else
                if (LCS[i + 1][j] > LCS[i][j + 1])
                {
                    LCS[i][j] = LCS[i + 1][j];
                    unde[i][j] = '2';
                }
                else
                {
                    LCS[i][j] = LCS[i][j + 1];
                    unde[i][j] = '3';
                }

}
void afisare()
{
    int i, j;
    fout << LCS[1][1] << '\n';
    i = 1; j = 1;
    while (i <= n && j <= m)
    {
        if (unde[i][j] == '1')
        {
            fout << a[i] << ' ';
            i++;
            j++;
        }
        else
            if (unde[i][j] == '2')
            {
                i++;
            }
            else
                j++;
    }
}