// cmlsc.cpp : Defines the entry point for the console application.
//
#include <stdio.h>
#define maxim(a,b) (a>=b?a:b)

int m,n,a[1025],b[1025],d[1025][1025],sir[1025],bst=0;

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(int j=1;j<=n;j++)
			if(a[i]==b[j])
				d[i][j]=d[i-1][j-1]+1;
			else
				d[i][j]=maxim(d[i][j-1],d[i-1][j]);

	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(int i=bst;i;i--)
		printf("%d ",sir[i]);

	return 0;


}