#include <fstream>
#define NMAX 1048

using namespace std;

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

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

int n, m, A[NMAX], B[NMAX];
int LCS[NMAX][NMAX];

int main()
{
    citire();
    pd();
    afisare();
    return 0;
}

void citire()
{
    int i;
    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];
            else
                if (LCS[i][j+1] > LCS[i+1][j])
                    LCS[i][j] = LCS[i][j+1];
                else
                    LCS[i][j] = LCS[i+1][j];
        }
}

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