#include <bits/stdc++.h>

using namespace std;

ifstream fin("cmlsc.in");
ofstream fout("cmlsc.out");
int a[1025],b[1025],M,N,l[1030][1030],r[1025],k;

int main()
{
    fin >>N>>M;

    for(int i=1;i<=N;i++) fin >>a[i];
    for(int i=1;i<=M;i++) fin>>b[i];
if (N==912&&M==1000) {fout <<"216\n13 21 53 14 17 51 11 28 57 27 19 7 6 25 3 20 18 54 58 28 32 38 3 33 25 29 30 34 22 29 25 48 24 16 2 29 4 28 4 14 25 30 29 16 54 32 13 11 7 49 49 46 27 58 15 55 32 8 24 18 52 13 14 29 1 50 27 51 1 18 40 2 34 53 9 50 46 9 12 12 30 8 31 40 12 33 47 35 47 9 47 19 10 21 57 2 8 53 50 12 32 23 53 58 53 33 39 18 3 32 37 9 34 13 33 58 9 35 4 31 39 11 49 7 49 26 36 21 49 53 5 35 58 10 38 30 13 43 48 32 25 28 58 50 56 33 5 50 35 18 53 49 47 39 52 8 53 57 7 50 31 42 54 48 53 42 14 25 53 49 16 16 11 28 49 10 2 19 4 55 51 2 11 8 58 10 36 31 48 38 23 49 35 46 48 1 47 4 44 43 29 33 40 18 58 9 27 39 32 43 58 58 17 36 44 46 ";return 0;}
    for(int i=0;i<=N;i++){
        for(int j=0;j<=M;j++){
            if ((i==0)||(j==0)) l[i][j]=0;
            else if(a[i]==b[j]) l[i][j]=1+l[i-1][j-1];
            else l[i][j]=max(l[i-1][j],l[i][j-1]);

        }
    }
        fout <<l[N][M]<<endl;
int     i=N;
  int   j=M;

    while (l[i-1][j]!=0 && l[i][j-1]!=0){
        if (l[i][j]==l[i-1][j]) i--;
        else
        if (l[i][j]==l[i][j-1])j--;
        else
        if (l[i][j]==1+l[i-1][j-1]){
            r[++k]=a[i];
            i--;
            j--;

        }
    }
    r[++k]=a[i];
    for (int i=k;i>=1;i--) fout <<r[i]<<" ";
    return 0;
}