#include <algorithm>
#include <iostream>
#include <fstream>
#include <iomanip>
#include <string>
#include <vector>
#include <bitset>
#include <stack>
#include <queue>
#include <deque>
#include <map>
#include <set>

using namespace std;

#ifdef LOCAL
ifstream fin("input.txt");
#define fout cout
#else
ifstream fin("cmlsc.in");
ofstream fout("cmlsc.out");
#endif

const int NMAX = 1050;

int n, m;
int a[NMAX], b[NMAX];
int dp[NMAX][NMAX];
int ans[NMAX];

void read() {
	fin >> n >> m;
	for (int i = 1; i <= n; i++)
		fin >> a[i];
	for (int i = 1; i <= m; i++)
		fin >> b[i];
}

void solve() {
	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;
	while (i && j) {
		if (a[i] == b[j]) {
			ans[dp[i][j]] = 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 = 1; i <= dp[n][m]; i++)
		fout << ans[i] << ' ';
}

int32_t main() {
	read();
	solve();
	return 0;
}