#include <iostream>
#include <fstream>

using namespace std;
int n, m, k;
int a[2000], b[2000];
int L[2000][2000], sol[2000];

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

int lcs() {
	for (int i = 1; i <= n; ++i) {
		for (int j = 1; j <= m; ++j) {
			if (a[i] == b[j]) {
				L[i][j] = L[i - 1][j - 1] + 1;
			}
			else
			{
				int s1 = L[i - 1][j];
				int s2 = L[i][j - 1];
				if (s1 > s2)
					L[i][j] = s1;
				else L[i][j] = s2;
			}
		}
	}
	return L[n][m];
}

void findlcs() {
	for (int i = n, j = m; i > 0;) {
		if (a[i] == b[j]) {
			sol[k] = a[i];  k++;
			i--;
			j--;
		}
		else
		{
			if (L[i - 1][j] < L[i][j - 1])
				--j;
			else
				--i;
		}
	}
}

void findlcsrec(int i, int j) {
	if (i >= 1 && j >= 1) {
		if (a[i] == b[j]) {
			findlcsrec(i - 1, j - 1);
			sol[k] = a[i];
			k++;
		}
		else {
			if (L[i - 1][j] < L[i][j - 1])
				findlcsrec(i, j - 1);
			else findlcsrec(i - 1, j);
		}
	}
}

int main() {
	in >> n >> m;

	for (int i = 1; i <= n; i++)
		in >> a[i];

	for (int i = 1; i <= m; i++)
		in >> b[i];

	out << lcs() << "\n";

	findlcsrec(n, m);

	for (int i = 0; i <= k - 1; i++) out << sol[i] << " ";
}