#include <fstream>
using namespace std;
ifstream fin("cmlsc.in");
ofstream fout("cmlsc.out");
int A[1025],B[1025],n,m;
int dp[1025][1025],sol;
void drum(int i,int j,int x){
    if(x!=0){
        if(A[i]==B[j]){
            drum(i-1,j-1,x-1);
            fout<<A[i]<<" ";
        }
        else{
            if(dp[i-1][j]>dp[i][j-1])
                drum(i-1,j,x);
            else
                drum(i,j-1,x);
        }
    }
}
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];
    for(int i=1;i<=n;i++)
        for(int j=1;j<=m;j++){
            if(A[i]==B[j])
                dp[i][j]=dp[i-1][j-1]+1;
            else
                dp[i][j]=max(dp[i][j-1],dp[i-1][j]);
        }
    fout<<dp[n][m]<<endl;
    drum(n,m,dp[n][m]);
    return 0;
}