#include <cstdio>
#include <algorithm>
#define N 1025

using namespace std;

int n, m, a[N], b[N], s[N][N];

void citire()
{
    scanf ("%d %d ", &n, &m);
    for (int i = 1; i <= n; ++ i)
        scanf ("%d ", &a[i]);
    for (int i = 1; i <= m; ++ i)
        scanf ("%d ", &b[i]);
}

void matrice()
{
    for (int i = 1; i <= n; ++ i)
        for (int j = 1; j <= m; ++ j)
            if (a[i] == b[j])
                s[i][j] = 1 + s[i-1][j-1];
            else
                s[i][j] = max(s[i-1][j], s[i][j-1]);
    printf ("%d\n", s[n][m]);
}

void afisare(int i,int j)
{
    if (i == 0 || j == 0)
        return;
    if (a[i] == b[j])
    {
        afisare(i-1, j-1);
        printf ("%d ", a[i]);
    }
    else if (s[i-1][j] < s[i][j-1])
        afisare(i, j-1);
    else
        afisare(i-1, j);
}

int main()
{
    freopen("cmlsc.in", "r", stdin);
    ///freopen("cmlsc.out", "w", stdout);
    citire();
    matrice();
    afisare(n, m);
    printf ("\n");
    return 0;
}