#include <fstream>
#include <vector>
#include <algorithm>

using namespace std;

ifstream fin("cmlsc.in");
ofstream fout("cmlsc.out");

const int maxx = (1<<10)+1;

int n, m;
int a[maxx], b[maxx], c[maxx][maxx];
vector <int> ans;
void bordare();

int main() {
    fin >> n >> m;
    for (int i = 0; i < n; i++)
        fin >> a[i];

    for (int i = 0; i < m; i++)
        fin >> b[i];
/*
    for (int i = 0; i < n; i++)
        fout << a[i] << " ";
    fout << endl;
    for (int i = 0; i < m; i++)
        fout << b[i] << " ";
    fout << endl;
*/
    bordare();

    for(int i=1;i<=n;i++)
        for(int j=1;j<=m;j++)
            if(a[i-1]==b[j-1])
                c[i][j]=1+c[i-1][j-1];
            else
                c[i][j]=max(c[i-1][j],c[i][j-1]);

/*
    for(int i=0;i<=n;i++)
    {
        for(int j=0;j<=m;j++)
            fout<<c[i][j]<<" ";
        fout<<"\n";
    }
*/

    for(int i=n,j=m;i>0 && j>0;)
    {
        if(a[i-1]==b[j-1])
        {
            ans.push_back(a[i-1]);
            i--;
            j--;
            continue;
        }
        else if(c[i-1][j]>c[i][j-1])
        {
            i--;
            continue;
        }
        else
        {
            j--;
            continue;
        }
    }

    fout<<ans.size()<<'\n';

    for(int i=ans.size()-1;i>=0;i--)
        fout<<ans[i]<<" ";

    return 0;

}
void bordare()
{
    for(int j=0;j<=m;j++)
        c[0][j]=0;
    for(int i=0;i<=n;i++)
        c[i][0]=0;
}