#include <fstream>
using namespace std;
ifstream cin("cmlsc.in");
ofstream cout("cmlsc.out");
int i, j, n, m, k;
int a[1030], b[1030], d[1030][1030], v[1030];
int main() {
    cin>>n>>m;
    for(i=1;i<=n;i++)
        cin>>a[i];
    for(j=1;j<=m;j++)
        cin>>b[j];
    for(i=1;i<=n;i++)
        for(j=1;j<=m;j++){
           if(a[i]==b[j])
                d[i][j]=d[i-1][j-1]+1;
           else
                d[i][j]=max(d[i-1][j], d[i][j-1]);
        }
    cout<<d[n][m];
    i=n;
    j=m;
    while(i>=1 && j>=1){
        if(a[i]==b[j]){
            v[++k]=a[i];
            i--;
            j--;
        }
        else{
            if(d[i-1][j]>d[i][j-1])
                i--;
            else
                j--;
        }
    }
    cout<<"\n";
    for(i=k;i>=1;i--)
        cout<<v[i]<<" ";


}