#include <iostream>
#include <cstdio>
#include <stack>

using namespace std;

int a[1025], b[1025], lung[1025][1025], ant[1025], n, m;

int main()
{
	int i, j;
	freopen("cmlsc.in", "r", stdin);
	freopen("cmlsc.out", "w", stdout);
	scanf("%d%d", &n, &m);
	for (i = 1; i <= n; i++) scanf("%d", &a[i]);
	for (i = 1; i <= m; i++) scanf("%d", &b[i]);

	for (i = 1; i <= n; i++)
		for (j = 1; j <= m; j++) {
			ant[i] = ant[i - 1];
			if (a[i] == b[j]) {
				lung[i][j] = 1 + lung[i - 1][j - 1];
				ant[j] = i;
			}
			else lung[i][j] = max(lung[i - 1][j], lung[i][j - 1]);
		}
	printf("%d\n", lung[i][j]);

	stack<int> s;
	i = m;
	while (i != ant[i]) {
		s.push(a[ant[i]]);
		i = ant[i];
	}
	while (!s.empty()) printf("%d ", s.top()), s.pop();

	return 0;
}