#include <fstream>
#define DMAX 1032

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

int n, m, LCS[DMAX][DMAX], a[DMAX], b[DMAX];
char unde[DMAX][DMAX];

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

int main()
{
    citire();
    pd();
    afisare();
    return 0;
}

void citire()
{
    int i;
    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';
}