#include <fstream>
#include <vector>
#include <algorithm>

using namespace std;

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

const int maxx = (1 << 10) + 1;

int n, m;
int a[maxx], b[maxx], c[maxx][maxx];
vector<int> ans;
void bordare();


int main() {

    fin >> n >> m;
    for (int i = 0; i < n; i++)
        fin >> a[i];

    for (int i = 0; i < m; i++)
        fin >> b[i];

    bordare();


    for (int i = 1; i <= n; i++)
        for (int j = 1; j <= m; j++)
            if (a[i - 1] == b[j - 1])
                c[i][j] = 1 + c[i - 1][j - 1];
            else
                c[i][j] = max(c[i - 1][j], c[i][j - 1]);


    for (int i = n, j = m; i > 0 && j > 0;) {
        if (a[i - 1] == b[j - 1]) {
            ans.push_back(a[i - 1]);
            i--;
            j--;
            continue;
        } else if (c[i - 1][j] == c[i][j - 1]) {
            i--;
            continue;
        } else {
            j--;
            continue;
        }
    }

    fout << ans.size() << '\n';
    sort(ans.rbegin(), ans.rend());
    for (int i = ans.size() - 1; i >= 0; i--)
        fout << ans[i] << " ";

    return 0;

}

void bordare() {

    for (int j = 0; j <= m; j++)
        c[0][j] = 0;

    for (int i = 0; i <= n; i++)
        c[i][0] = 0;
}