#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];
char unde[DMAX][DMAX];
int LCS[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(j=1;j<=m;j++)
        fin>>b[j];
}

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()
{
    fout << LCS[1][1] << '\n';
    int 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';
}