#include <bits/stdc++.h>
using namespace std;
ifstream in("cmlsc.in");
ofstream out ("cmlsc.out");
int v[1023], x[1023], d[1024][1024], sol[1023], k = 1;
int n, m;

int main() {
	in >> n >> m;
	for (int i = 1; i <= n; i++) in >> v[i];
	for (int i = 1; i <= m; i++) in >> x[i];

	for (int i = 1; i <= n; i++) {
		for (int j = 1; j <= m; j++) {
			if (v[i] == x[j])
			{
				d[i][j] = d[i-1][j-1] + 1;
				sol[k++] = v[i];
			}
			else
				d[i][j] = max(d[i-1][j], d[i][j-1]);
		}
	}

	out << d[n][m] << "\n";

	/*
	for (int i = 1; i <= n; i++) {
	    for (int j = 1; j <= m; j++)
	        cout << d[i][j] << ' ';
	    cout << '\n';
	}
	*/
	for(int i = 1; i < k; i++)
		out << sol[i] <<' ';
	return 0;
}