#include <stdio.h>

#define max(A, B) ((A > B) ? A : B)
#define N 1024

int main ()
{
	int FirstLength, SecondLength, A[N], B[N], D[N][N], sir[N], length = 0;

	freopen ("clmsc.in", "r", stdin);
    freopen ("cmlsc.out", "w", stdout);
 	
    
    scanf ("%d %d", &FirstLength, &SecondLength);
    for (int i = 1; i <= FirstLength; ++i)
        scanf ("%d", &A[i]);
    for (int i = 1; i <= SecondLength; ++i)
        scanf ("%d", &B[i]);
    
    for (int i = 1; i <= FirstLength; ++i)
        for (int j = 1; j <= SecondLength; ++j)
        	if (A[i] == B[j])
        		D[i][j] = 1 + D[i - 1][j - 1];
        	else
        		D[i][j] = max (D[i - 1][j], D[i][j - 1]);

    for (int i = FirstLength, j = SecondLength; i != 0; )
    	if (A[i] == B[j])
    		sir[++length] = A[i], --i, --j;
        else
        	if (D[i - 1][j] < D[i][j - 1])
        		--j;
        	else
        		--i;


    printf("%d\n", length);
   	for (int i = length; i != 0; --i)
   		printf("%d\n", sir[i]);

	return 0;
}