#include <bits/stdc++.h>

using namespace std;

const long long max_size = 1030;

int dp[max_size][max_size], a[max_size], b[max_size];

void solve ()
{
    int n, m;
    cin >> n >> m;
    for (int i = 1; i <= n; i++)
    {
        cin >> a[i];
    }
    for (int j = 1; j <= m; j++)
    {
        cin >> b[j];
    }
    for (int i = 1; i <= n; i++)
    {
        for (int j = 1; j <= m; j++)
        {
            if (a[i] == b[j])
            {
                dp[i][j] = dp[i - 1][j - 1] + 1;
            }
            else
            {
                dp[i][j] = max(dp[i - 1][j], dp[i][j - 1]);
            }
        }
    }
    vector <int> ans;
    int i = n, j = m;
    while (i >= 1 && j >= 1)
    {
        if (a[i] == b[j])
        {
            ans.push_back(a[i]);
            i--;
            j--;
        }
        else
        {
            if (dp[i - 1][j] > dp[i][j - 1])
            {
                i--;
            }
            else
            {
                j--;
            }
        }
    }
    reverse(ans.begin(), ans.end());
    cout << ans.size() << '\n';
    for (auto f : ans)
    {
        cout << f << " ";
    }
    cout << '\n';
}

signed main ()
{
#ifdef LOCAL
    freopen("test.in", "r", stdin);
    freopen("test.out", "w", stdout);
#else
    freopen("cmlsc.in", "r", stdin);
    freopen("cmlsc.out", "w", stdout);
#endif // LOCAL
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    long long tt;
    //cin >> tt;
    tt = 1;
    while (tt--)
    {
        solve();
    }
    return 0;
}