#include <fstream>
#define DMAX 1032
using namespace std;
ifstream fin("cmlsc.in");
ofstream fout("cmlsc.out");
int n, m;
int a[DMAX];
int b[DMAX];
int LCS[DMAX][DMAX];
char unde[DMAX][DMAX];

void citire();
void pd();
void afisare();

int main()
{
    citire();
    pd();
    afisare();
    return 0;
}
void citire()
{
    int i, j;
    fin >>n >>m;
    for (i=1; i<=n; i++) fin >>a[i];
    for (i=1; i<=m; i++) fin >>b[i];
}
void pd()
{
    int i, j;
    for (i=n; i>0; i--)
        for (j=m; j>0; j--)
            if (a[i]==b[j])
            {
                LCS[i][j]=1+LCS[i+1][j+1];
                unde[i][j]='1';
            }
            else if (LCS[i+1][j]>LCS[i][j+1])
            {
                LCS[i][j]=LCS[i+1][j];
                unde[i][j]='2';
            }
            else
            {
                LCS[i][j]=LCS[i][j+1];
                unde[i][j]='3';
            }

}
void afisare()
{
    int i, j;
    fout <<LCS[1][1]<<'\n';
    i=1;
    j=1;
    while(i<=n && j<=m)
    {
        if (unde[i][j]=='1')
        {
            fout <<a[i]<<' ';
            i++;
            j++;
        }
        else if (unde[i][j]=='2')
        {
            i++;
        }
        else
            j++;
    }
    fout <<'\n';
    fout.close();
}