#include <fstream>
#define IMAX 1032
using namespace std;

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

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

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++;
    }
    fout << '\n';
}

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