#include <fstream>

using namespace std;

int d[1030][1030], a[1030], b[1030];
int n, m, i, j;

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

void drum(int i, int j, int k) {
    if (k!=0) {
        if (a[i] == b[j]) {
            drum(i-1, j-1, k-1);
            fout<<a[i]<<" ";
        } else
            if (d[i-1][j] > d[i][j-1])
                drum(i-1, j, k);
            else
                drum(i, j-1, k);
    }
}

int main () {

    fin>>n>>m;
    for (i=1;i<=n;i++) {
        fin>>a[i];
    }
    for (i=1;i<=m;i++) {
        fin>>b[i];
    }

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

    fout<<d[n][m]<<"\n";

    drum(n, m, d[n][m]);

    return 0;
}