#include <fstream>
#define MAX 1050
using namespace std;
ifstream fin("cmlsc.in");
ofstream fout("cmlsc.out");
int n,m;
int a[MAX],b[MAX],lcs[MAX][MAX],unde[MAX][MAX];
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>=1; i--)
        for(j=m; j>=1; 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++;

    }
}