#include <fstream>
#include <stack>

using namespace std;

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

const int MAXN = 1024;
const int MAXM = 1024;
const int MAXVAL = 256;

int a[MAXN + 1], b[MAXM + 1], dp[MAXN + 2][MAXM + 2];
int n, m;

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];

	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]);
		}
	}

	out << dp[n][m] << '\n';
	// for (int i = 1; i <= n; ++ i) {
	// 	for (int j = 1; j <= m; ++ j) {
	// 		out << dp[i][j] << ' ';
	// 	}
	// 	out << '\n';
	// }

	stack <int>ans;
	int i = n, j = m;;

	while (i >= 1 && j >= 1 && ans.size() < dp[n][m]) {
    if (a[i] == b[j]) {
      ans.push(a[i]);
      -- i, -- j;
    }
    else {
      if (dp[i - 1][j] == dp[i][j])
        -- i;
      else
        -- j;
    }
	}

	while (ans.size()) {
		out << ans.top() << ' ';
		ans.pop();
	}


	return 0;
}