#include <iostream>
#include <fstream>

#define lmax 1024

using namespace std;

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

int m, n, a[lmax], b[lmax], d[lmax][lmax], sir[lmax], best;

/*int max(int a, int b)
{
     (a > b) ? a : b;
}*/

int main()
{
    fin>>m>>n;
    for (int i=1; i<=m; ++i)
        fin>>a[i];
    for (int i=1; i<=n; ++i)
        fin>>b[i];

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

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

    fout<<best<<'\n';
    for (int i=best; i>=1; --i)
        fout<<sir[i]<<" ";
    return 0;
}