#include <bits/stdc++.h>

using namespace std;
ifstream fin("cmlsc.in");
ofstream fout("cmlsc.out");
int n, m, a[1030], b[1030], dp[1030][1030];
int main()
{
    int i, j;
    fin >> n >> m;
    for (i = 1; i <= n; i++)
        fin >> a[i];
    for (j = 1; j <= m; j++)
        fin >> b[j];

    for (i = n; i >= 1; i--)
        for (j = m; j >= 1; 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[1][1] << "\n";
    i = j = 1;
    while (i <= n and j <= m)
    {
        if (a[i] == b[j])
        {
            fout << a[i] << " ";
            i++;
            j++;
        }
        else if (dp[i + 1][j] <= dp[i][j + 1])
            j++;
        else
            i++;

    }


    return 0;
}