#include <bits/stdc++.h>

FILE* fin = fopen("cmlsc.in", "r");
FILE* fout = fopen("cmlsc.out", "w");

int n, m, a[1025], b[1025], best[1025][1025], sol[1025], bst;

int main() {
    fscanf(fin, "%d%d", &n, &m);

    for (int i = 1; i <= n; ++i)
        fscanf(fin, "%d", &a[i]);

    for (int i = 1; i <= m; ++i)
        fscanf(fin, "%d", &b[i]);

    for (int i = 1; i <= n; ++i)
        for (int j = 1; j <= m; ++j) {
                if (a[i] == b[j])
                    best[i][j] = best[i - 1][j - 1] + 1;
                else
                    best[i][j] = std::max(best[i - 1][j], best[i][j - 1]);
            }

    /*for (int i = 1; i <= n; ++i) {
            for (int j = 1; j <= m; ++j)
                std::cout << best[i][j] << ' ';

            std::cout << '\n';
        }*/

    while (n && m) {
            if (a[n] == b[m])
                sol[++bst] = a[n], --n, --m;
            else if (best[n][m - 1] > best[n - 1][m])
                --m;
            else
                --n;
        }

    fprintf(fout, "%d\n", bst);

    for (int i = bst; i >= 1; --i)
        fprintf(fout, "%d ", sol[i]);

    fclose(fin), fclose(fout);
    return 0;
}