#include <fstream>
#include <vector>
using namespace std;
ifstream fin ("cmlsc.in");
ofstream fout ("cmlsc.out");
int n, m, a[1027], b[1027], dp[1027][1027];

int main()
{
    fin >> n >> m;
    for (int i = 1; i <= n; i++)
        fin >> a[i];
    for (int j = 1; j <= m; j++)
        fin >> b[j];
    for (int i = 1; i <= n; i++)
        for (int j = 1; j <= m; j++)
            if (a[i]==b[j])
                dp[i][j] = dp[i-1][j-1]+1;
            else
                dp[i][j] = max(dp[i-1][j], dp[i][j-1]);
    int i = n, j = m;
    vector <int> r;
    while(i > 0 && j > 0){
        if(a[i] == b[j])
            r.push_back(a[i]), i--, j--;
        else
            if (dp[i-1][j] > dp[i][j-1]) i--;
            else j--;
    }
    fout << dp[n][m] <<'\n';
    for (int i = r.size()-1; i >= 0; i--)
        fout << r[i] <<" ";
    return 0;
}