#include <fstream>
#include <vector>
#include <stack>
#include <algorithm>

#define BF 1
#define F  2
#define B  3

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

typedef vector<int> Vektor;
typedef vector<int>::iterator Iterator;
typedef vector<int>::const_iterator cIterator;

vector<int> x, y;
stack<int> v;
int n, m, i, j, temp;
int a[1030][1030];
int b[1030][1030];
int write_vector (const Vektor& t)
{
    cIterator i;
    for (i=t.begin(); i<t.end(); i++)
        g << *i << " ";
    g << "\n";
    return 0;
}
int write_matrix ()
{
    for (int i=0; i<n; i++)
    {
        for (int j=0; j<m; j++)
        {
            g << a[i][j] << " ";
        }
        g << "\n";
    }
    return 0;
}
int main()
{
    f >> n >> m;
    x.push_back(0);
    y.push_back(0);

    for (i=1; i<=n; i++)
    {
        f >> temp;
        x.push_back(temp);
    }
    for (i=1; i<=m; i++)
    {
        f >> temp;
        y.push_back(temp);
    }
    n++; m++;

    for (i=1; i<=n; i++)
    {
        for (j=1; j<=m; j++)
        {
            if (x[i] == y[j])
            {
                a[i][j] = a[i-1][j-1] + 1;
                b[i][j] = BF;
            }
            else
            {
                if (a[i-1][j] > a[i][j-1])
                {
                    a[i][j] = a[i-1][j];
                    b[i][j] = F;
                }
                else
                {
                    a[i][j] = a[i][j-1];
                    b[i][j] = B;
                }
            }
        }
    }

    g << a[n-1][m-1] << "\n";
    //write_matrix();

    int db = a[n-1][m-1];
    i = n-1;
    j = m-1;
    while (db)
    {
        if (b[i][j] == BF)
        {
            v.push (x[i]);
            db--;
            i--, j--;
        }
        else if (b[i][j] == F)
        {
            i--;
        }
        else if (b[i][j] == B)
        {
            j--;
        }
    }
    while (!v.empty())
    {
        g << v.top() << " ";
        v.pop();
    }
}