#include <fstream>
#include <vector>

int main() {
	std::ifstream fin("cmisc.in");
	std::ofstream fout("cmisc.out");

	int sa, sb;
	fin >> sa >> sb;

	std::vector<int> a(sa), b(sb);
	for (int i = 0; i < sa; i++)
		fin >> a[i];
	for (int i = 0; i < sb; i++)
		fin >> b[i];

	std::vector<std::vector<int>> c(sa, std::vector<int>(sb));
	for (int i = 0; i < sa; i++)
		c[i][0] = a[i] == b[0] ? 1 : 0;
	for (int i = 0; i < sb; i++)
		c[0][i] = a[0] == b[i] ? 1 : 0;
	for (int i = 1; i < sa; i++)
		for (int j = 1; j < sb; j++)
			c[i][j] = a[i] == b[j] ? c[i - 1][j - 1] + 1 
		                           : std::max(c[i - 1][j], c[i][j - 1]);

    auto mlen = c[sa-1][sb-1];
    std::vector<int> rec(mlen);
    int x = sa-1, y = sb-1;
    while (mlen) {
    	if (a[x] == b[y]) {
    		rec[--mlen] = a[x];
    		x--;
    		y--;
    	} else if (c[x-1][y] == c[x][y]) {
    		x--;
    	} else {
    		y--;
    	}
    }

    fout << c[sa-1][sb-1] << std::endl;
    for (const auto& r : rec)
    	fout << r << " ";
	return 0;
}