#include<fstream>

using namespace std;

int matrice[1030][1030];

int LCS(int *s1,int *s2,int Ls1,int Ls2)
{

    for(int i=1;i<=Ls1;i++)
    {
        for(int j=1;j<=Ls2;j++)
        {
            if(s1[i]==s2[j])
                matrice[i][j]=matrice[i-1][j-1]+1;
            else
            {
                int maxim=matrice[i][j-1];
                if(maxim<matrice[i-1][j])
                    maxim=matrice[i-1][j];
                matrice[i][j]=maxim;
            }

        }
    }
    return matrice[Ls1][Ls2];
}

int main()
{
    ifstream fin("cmlsc.in");
    ofstream fout("cmlsc.out");
    int Ls1,Ls2;
    int s1[1030];
    int s2[1030];
    fin>>Ls1>>Ls2;
    for(int i=1;i<=Ls1;i++)
        fin>>s1[i];
    for(int i=1;i<=Ls2;i++)
        fin>>s2[i];
    fout<<LCS(s1,s2,Ls1,Ls2) << '\n';
    int n = Ls1;
    int m = Ls2;
    int contor = 1, vec[1030];
    while(n > 0 && m > 0){
        if(s1[n] == s2[m]){
            vec[contor] = s1[n];
            contor++;
            n--; m--;
        }
        else{
            if(matrice[n-1][m] > matrice[n][m-1]){
                n--;
            }
            else{
                m--;
            }
        }
    }
    for(int i=contor-1; i>=1; i--){
        fout << vec[i] << ' ';
    }

    return 0;
}