#include <fstream>
#define DMAX 1030
using namespace std;
ifstream fin("cmlsc.in");
ofstream fout("cmlsc.out");
int n, m;
int a[DMAX];
int b[DMAX];
int lgmax[DMAX][DMAX];
int unde[DMAX][DMAX];
int main()
{
    int i, j;
    fin >> n >> m;
    for(i = 1; i <= n; i++) fin >> a[i];
    for(i = 1; i <= m; i++) fin >> b[i];
    for(i = n; i > 0; i--)
        for(j = m; j > 0; j--)
            if(a[i] == b[j])
            {
                lgmax[i][j] = 1 + lgmax[i + 1][j + 1];
                unde[i][j] = 1;
            }
            else
                if(lgmax[i + 1][j] > lgmax[i][j + 1])
                {
                    lgmax[i][j] = lgmax[i + 1][j];
                    unde[i][j] = 2;
                }
                else
                {
                    lgmax[i][j] = lgmax[i][j + 1];
                    unde[i][j] = 3;
                }
    //afisare
    fout << lgmax[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();
    return 0;
}