#include <fstream>
#include <iostream>

using namespace std;
const int N = 1030;
ifstream fin("cmlsc.in");
ofstream fout("cmlsc.out");

int dp[N][N];
int len, n, m;
int sol[N], a[N], b[N];

void READ()
{
    fin >> m >> n;
    for (int i = 1; i <= m; i++)
        fin >> a[i];
    for (int i = 1; i <= n; i++)
        fin >> b[i];
        fin.close();
}
void DP()
{
    for (int i = 1; i <= m; i++)
        for (int j = 1; j <= n; j++)
            if (a[i] == b[j])
                dp[i][j] = 1 + dp[i - 1][j - 1];
            else
                dp[i][j] = max(dp[i-1][j], dp[i][j - 1]);

}
void SC()
{
    for (int i = m; i > 0;)
        for (int j = n; j > 0 and i > 0;)
        if (a[i] == b[j])
        {
             sol[++len] = a[i];
             i--;
             j--;
        }
        else if (dp[i-1][j] < dp[i][j-1])
            --j;
        else
            --i;
///152 101 229 246 168 17 168 69 134 44 200 11 195 225 50 70 82 221 240 173 62 125 145 117 151 194 92 99 20 183 199 172 34 164
}
void DISPLAY()
{
    fout << dp[m][n] << "\n";
    for (int i = len; i >= 1; i--)
        fout << sol[i] << " ";
    fout.close();
}

int main()
{
    READ();
    DP();
    SC();
    DISPLAY();

    return 0;
}