#include <iostream>
#include <fstream>

using namespace std;

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

#define maxim(a, b) ((a > b) ? a : b)
#define MAX 1024

int main()
{
	int n, m, i, j, max = 0;
	int A[MAX], B[MAX], D[MAX][MAX], result[MAX];

	input >> n >> m;

	for (i = 1; i <= n; i++)
	{
		input >> A[i];
	}

	for (j = 1; j <= m; j++)
	{
		input >> B[j];
	}

	for (i = 1; i <= n; i++)
	{
		for (j = 1; j <= m; j++)
		{
			if (A[i] == B[j])
			{
				D[i][j] = 1 + D[i - 1][j - 1];
			}
			else
			{
				D[i][j] = maxim(D[i][j - 1], D[i - 1][j]);
			}
		}
	}

	for (i = n, j = m; i; )
	{
		if (A[i] == B[j])
		{
			result[++max] = A[i];
			i--;
			j--;
		}
		else if (D[i][j - 1] > D[i - 1][j])
		{
			j--;
		}
		else
		{
			i--;
		}
	}

	output << max << "\n";
	for (i = max; i; i--)
	{
		output << result[i] << " ";
	}

	return 0;
}