#include <fstream>
#include <algorithm>

using namespace std;

ifstream cin("cmlsc.in");
ofstream cout("cmlsc.out");

int v1[1030];
int v2[1030];
int dp[1030][1030];

void afisare_nr(int i, int j){
    if (i == 0 || j == 0){
        return;
    }
    if (v1[i] == v2[j]){
        afisare_nr(i-1, j-1);
        cout << v1[i] << " ";
    }
    else if (dp[i-1][j] > dp[i][j-1]){
        afisare_nr(i-1, j);
    }
    else{
        afisare_nr(i, j-1);
    }
}

int main()
{
    int n, m;
    cin >> n >> m;
    for (int i = 1; i <= n; i++){
        cin >> v1[i];
    }
    for (int i = 1; i <= m; i++){
        cin >> v2[i];
    }
    for (int i = 1; i <= n; i++){
        for (int j = 1; j <= m; j++){
            if (v1[i] == v2[j]){
                dp[i][j] = dp[i-1][j-1] + 1;
            }
            else{
                dp[i][j] = max(dp[i-1][j], dp[i][j-1]);
            }
        }
    }
    cout << dp[n][m] << '\n';
    afisare_nr(n, m);
    return 0;
}