#include <fstream>
#include <algorithm>
using namespace std;
ifstream in("cmlsc.in");
ofstream out("cmlsc.out");

int a[1030], b[1030];
int lcs[1030][1030];
int n, m;
int index, sir[1030];
void citire()
{
	in >> n >> m;
	for (int i = 1; i <= n; i++)
	{
		in >> a[i];
	}
	for (int j = 1; j <= m; j++)
	{
		in >> b[j];
	}
}

void afisare()
{
	for (int i = 1; i <= n; i++)
	{
		for (int j = 1; j <= m; j++)
		{
			out << lcs[i][j] << ' ';
		}
		out << '\n';
	}
}
int main()
{
	citire();
	
	for (int i = 1; i <= n; i++)
	{
		for (int j = 1; j <= m; j++)
		{
			if (a[i] == b[j])
			{
				sir[index++] = a[i];
				lcs[i][j] = 1 + lcs[i - 1][j - 1];
			}
			else
				lcs[i][j] = max(lcs[i - 1][j], lcs[i][j - 1]);
		}
	}

	out << lcs[n][m]<<'\n';
	for (int i = 0; i < index; i++)
		out << sir[i] << ' ';
}