#include <stdio.h>
#define maxim(a, b) ((a > b) ? a : b)
#define NMax 1024
int M, N, A[NMax], B[NMax], D[NMax][NMax], sir[NMax], bst;
int main()
{
	int i, j;
	freopen("cmlsc.in", "r", stdin);
	freopen("cmlsc.out", "w", stdout);
	scanf("%d %d", &M, &N);
	for (i=1;i<=M;i++)
		scanf("%d", &A[i]);
	for (i=1;i<=N;i++)
		scanf("%d", &B[i]);
	for (i=1;i<=M;i++)
		for (i=1;i<=N;i++)
			if (A[i] == B[j])
				D[i][j] = 1 + D[i-1][j-1];
			else
				D[i][j] = maxim(D[i-1][j], D[i][j-1]);
	for (i = M, j = N; i; )
		if (A[i] == B[j])
			sir[++bst] = A[i], --i, --j;
		else 
			if (D[i-1][j] < D[i][j-1])
				--j;
			else
				--i;
	printf("%d\n", bst);
	for (i = bst; i; --i)
		printf("%d ", sir[i]);
	return 0;
}