#include <fstream>
using namespace std;

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

#define NMAX 1050

int a[NMAX], b[NMAX];
int dp[NMAX][NMAX];
int sir[NMAX];

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]);
            }
        }
    }

    int nr = 0;
    int i = n, j = m;
    while (j) {
        if (a[i] == b[j]) {
            sir[++nr] = a[i];
            i--;
            j--;
        } else if (dp[i - 1][j] > dp[i][j - 1]) {
            i--;
        } else {
            j--;
        }
    }

    fout << nr << '\n';
    for (int i = nr; i >= 1; --i) {
        fout << sir[i] << ' ';
    }
    return 0;
}