#include<fstream>
using namespace std;
ifstream in("cmlsc.in");
ofstream out("cmlsc.out");

int a[1025], b[1025], c[1025][1025], n, m, k, v[1025];

int main()
{
    int i, j;
    in >> n >> m;
    for(i = 1; i <= n; i++)
        in >> a[i];
    for(i = 1; i <= m; i++)
        in >> b[i];

    for(i = 1; i <= n; i++)
        for(j = 1; j <= m; j++)
            if(a[i] == b[j])
                c[i][j] = c[i-1][j-1] + 1;
            else
                if(c[i-1][j] >= c[i][j-1])
                    c[i][j] = c[i-1][j];
                else
                    c[i][j] = c[i][j-1];
    out << c[n][m] << endl;

    i = n;
    j = m;
    k = c[n][m];
    while(i && j)
    {
        if(a[i] == b[j])
        {
            v[k--] = a[i];
            i--;
            j--;
        }
        else
            if(c[i-1][j] >= c[i][j-1])
                i--;
            else
                j--;
    }
    k = c[n][m];
    for(i = 1; i <= k; i++)
        out << v[i] << " ";

    in.close();
    out.close();
    return 0;
}