#include <iostream>
#include <random>
#include <fstream>
#include <stack>
#include <bitset>
#include <unordered_map>
using namespace std;

ifstream fin("cmlsc.in");
ofstream fout("cmlsc.out");
int a[1025],b[1025];
int dp[1025][1025];
int main()
{
    int n, m;
    fin >> n >> m;
    for (int i = 1; i <= n; i++)
        fin >> a[i];
    for (int i = 1; i <= m; i++)
        fin >> b[i];
    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]);
        }
    fout << dp[n][m] << "\n";
    stack<int> st;
    int i = n, j = m;
    while (i >= 1)
    {
        if (a[i] == b[j])
            st.push(a[i]), i--, j--;
        else
        {
            if (dp[i - 1][j] > dp[i][j - 1])
                i--;
            else
                j--;
        }
    }
    while (!st.empty())
    {
        fout << st.top() << " ";
        st.pop();
    }
    return 0;
}