#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>

#pragma GCC optimize ("O1")
#pragma GCC optimize ("O2")
#pragma GCC optimize ("O3")
#pragma GCC optimize ("Ofast")
#pragma GCC optimize ("unroll-loops")
#pragma GCC target ("avx2")

using namespace std;
using namespace __gnu_pbds;

#define ordered_set tree <long long, null_type, less<long long>, rb_tree_tag, tree_order_statistics_node_update>
#define lsb(x)(x & (-x))

const int 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]);
            }
        }
    }
    int i = n, j = m;
    vector <int> v;
    while (i > 0 && j > 0)
    {
        if (a[i] == b[j])
        {
            v.push_back(a[i]);
            i--;
            j--;
        }
        else
        {
            if (dp[i - 1][j] > dp[i][j - 1])
            {
                i--;
            }
            else
            {
                j--;
            }
        }
    }
    cout << v.size() << '\n';
    reverse(v.begin(), v.end());
    for (auto f : v)
    {
        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;
}