#include <fstream>
using namespace std;
ifstream fin("cmlsc.in");
ofstream fout("cmlsc.out");
int main()
{   
     
    int M[1050];
    int N[1050];
    int Rez[1050];
    int m,n;
    fin >> m;
    fin >> n;
    int lungime = 0;
 
    for (int i = 0 ; i < m; i ++)
        fin >> M[i];
    for (int i = 0 ; i < n; i ++)
        fin >> N[i];
    int z = 0;
    if (m < n) {
        for (int i = 0; i < m; i ++){
             
            for (int x = z; x < n ; x++){
                if (M[i] == N[x]){
                    z = x;
                    Rez[lungime] = M[i];
                    lungime ++;
                    break;
                }
            }
        }
 
 
    }else {
        for (int i = 0; i < n; i ++){
             
            for (int x = z; x < m ; x++){
                if (N[i] == M[x]){
                    z = x;
                    Rez[lungime] = N[i];
                    lungime ++;
                    break;
                }
            }
        }
 
 
    }
    fout << lungime << "\n";
    for (int i = 0 ; i < lungime; i++){
        fout << Rez[i] << " ";
    }
}