#include <fstream>

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<1 || j<1){
        return;
    }
    if (dp[i-1][j-1] == dp[i][j] - 1 && dp[i-1][j] == dp[i][j] - 1 && dp[i][j-1] == dp[i][j] - 1){
        afisare_nr(i-1, j-1);
        cout<<v1[i]<<" ";
    }
    else{
        if (dp[i-1][j] == dp[i][j] && dp[i][j-1] == dp[i][j]){
            afisare_nr(i-1, j);
        }
        if (dp[i-1][j] == dp[i][j] - 1 && dp[i][j-1] == dp[i][j]){
            afisare_nr(i, j-1);
        }
        if (dp[i-1][j] == dp[i][j] && dp[i][j-1] == dp[i][j] - 1){
            afisare_nr(i-1, j);
        }
    }
}

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][j-1], dp[i-1][j]);
            }
            //cout<<dp[i][j]<<" ";
        }
        //cout<<'\n';
    }
    cout<<dp[n][m]<<'\n';
    afisare_nr(n,m);
    return 0;
}