#include <bits/stdc++.h>

using namespace std;

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

int main() {
    int n, m;
    in >> n >> m;

    std::vector<int> a(n, 0);
    std::vector<int> b(m, 0);

    for (int i = 0; i < n; i++)
        in >> a[i];

    for (int i = 0; i < m; i++)
        in >> b[i];

    std::vector<std::vector<int>> dp(n + 1, std::vector(m + 1, 0));

    for (int i = 1; i <= n; i++)
        for (int j = 1; j <= m; j++) {
            if (a[i - 1] == b[j - 1]) {
                dp[i][j] = max(dp[i][j], dp[i - 1][j - 1] + 1);
            } else {
                dp[i][j] = max(dp[i - 1][j - 1], max(dp[i - 1][j], dp[i][j - 1]));
            }
        }
    
    out << dp[n][m] << '\n';

    int l = n, r = m;
    std::vector<int> ans;

    while (l > 0 && r > 0) {
        if (a[l - 1] == b[r - 1]) {
            ans.push_back(a[l - 1]);
            l--;
            r--;
        } else {
            if (dp[l - 1][r] > dp[l][r - 1]) {
                l--;
            } else {
                r--;
            }
        }
    }

    for (int i = ans.size() - 1; i >= 0; i--) {
        out << ans[i] << ' ';
    }
}