#include <fstream>
#define L 1028
using namespace std;

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

int m, n, a[L], b[L], d[L][L];
int s[L], qt;
int main()
{
    f >> n >> m;
    for (int i = 1; i <= n; i++)
        f >> a[i];
    for (int i = 1; i <= m; i++)
        f >> b[i];
    for (int i = 1; i <= n; i++)
    for (int 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]);
    for (int i = n, j = m; i;){
        if (a[i] == b[j]){
            s[++qt] = a[i];
            i--; j--;
        }
        else if (d[i][j - 1] < d[i - 1][j])
            i--;
        else
            j--;
    }
    g << d[n][m] << '\n';
    for (int i = qt; i >= 1; i--)
        g << s[i] <<  " ";

    return 0;
}