#include <fstream>

#define Max 1024

using namespace std;

int main()
{
	int sirA[Max], sirB[Max], solutie[Max];
	int mat[Max][Max];
	int lung_A, lung_B, lung_MAX = 0;
	int i, j;

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

	inFILE >> lung_A >> lung_B;

	for (i = 1; i <= lung_A; i++)
	{
		inFILE >> sirA[i];
	}

	for (j = 1; j <= lung_B; j++)
	{
		inFILE >> sirB[j];
	}

	for (i = 1; i <= lung_A; i++)
	{
		for (j = 1; j <= lung_B; j++)
		{
			if (sirA[i] == sirB[j])
				mat[i][j] = mat[i-1][j-1] + 1;
			else
				mat[i][j] = max(mat[i-1][j],mat[i][j-1]);
		}
	}

	i = lung_A;
	j = lung_B;

	while (mat[i][j])
	{
		while (mat[i][j] == mat[i-1][j])
			i--;
		while (mat[i][j] == mat[i][j-1])
			j--;

		lung_MAX++;
		solutie[lung_MAX] = sirA[i];
		i--;
		j--;
	}

	outFILE << mat[lung_A][lung_B] << "\n";

	for (i = lung_MAX; i >= 1; --i)
		outFILE << solutie[i] << " ";

	// system("pause");
	return 0;
}