#include <fstream>
#define maxim(a, b) ((a > b) ? a : b)
using namespace std;
ifstream fin("cmlsc.in");
ofstream fout("cmlsc.out");
int m,n,a[1024],b[1024],d[1024][1024],sir[1024],bst;
int main()
{
    int i,j;
    fin>>m>>n;
    for(i=1;i<=m;i++)
        fin>>a[i];
    for(i=1;i<=n;i++)
        fin>>b[i];

    for(i=1;i<=m;i++)
        for(j=1;j<=n;j++)
            if(a[i]==b[j])
                d[i][j]=1+d[i-1][j-1];
            else
                d[i][j]=maxim(d[i-1][j],d[i][j-1]);
    for (i = m, j = n; i; )
        if (a[i] == b[j])
            sir[++bst] = a[i], --i, --j;
        else if (d[i-1][j] < d[i][j-1])
            --j;
        else
            --i;
    fout<<bst<<'\n';
    for (i = bst; i; --i)
        fout<<sir[i]<<" ";
}