#include <bits/stdc++.h>
using namespace std;

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

int n, m;
int a[1030], b[1030];
int dp[1030][1030];
vector<int> sol;

int main()
{
    int i, j;
    fin >> n >> m;
    for (i = 1; i <= n; i++)
        fin >> a[i];
    for (i = 1; i <= m; i++)
        fin >> b[i];
    for (i = 1; i <= n; i++)
        for (j = 1; j <= m; j++)
            if (a[i] != b[j]) dp[i][j] = max(dp[i - 1][j], dp[i][j - 1]);
            else dp[i][j] = dp[i - 1][j - 1] + 1;
    fout << dp[n][m] << "\n";
    i = n; j = m;
    while (i > 0 && j > 0)
        if (a[i] == b[j])
        {
            sol.push_back(a[i]);
            i--; j--;
        }
        else if (dp[i][j - 1] > dp[i - 1][j])
            j--;
        else i--;
    for (i = sol.size() - 1; i >= 0; i--)
        fout << sol[i] << " ";
    fout << "\n";
    fin.close();
    fout.close();
    return 0;
}
/**


  1 7 3 9 8
7 0 1 1 1 1
5 0 1 1 1 1
8 0 1 1 1 2
*/