#include <algorithm>
#include <iostream>
#include <vector>
#include <fstream>
using namespace std;
ifstream fin("cmlsc.in");
ofstream fout("cmlsc.out");
int n, m, a[1030], b[1030], dp[1030][1030];
int main() {
    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]);
        }
    }
    int i = n, j = m;
    vector<int> raspuns;
    while (i > 0 && j > 0) {
        if (a[i] == b[j]) {
            raspuns.push_back(a[i]);
            i --;
            j --;
        } else {
            if (dp[i-1][j] > dp[i][j-1])
                i --;
            else
                j --;
        }
    }
    fout << dp[n][m] << '\n';
    for (int i = raspuns.size() - 1; i >= 0; i --)
        fout << raspuns[i] << ' ';
    return 0;
}

// dp[n][m]

// dp[i][j] = lungimea celui mai lung subsir comun pana la pozitia i
//            in primul sir si pana la pozitia j in al doilea sir

// dp[i][j] = dp[i-1][j-1] + 1, daca a[i] == b[j]
//            max(dp[i-1][j], dp[i][j-1]), daca a[i] != b[j]


// 1 2 3 4 5 9 10 11
// 1 3 5 6

// i = 5
// j = 4
// dp[i-1][j-1] = 2
// dp[i][j] = 3