#include <stdio.h>
long i,j,h,n,m;
unsigned char a[1034],b[1034],v[1034];
int mt[-1034..1034][-1034..1034];

int main()
{
	freopen("cmlsc.in","r",stdin);
	freopen("cmlsc.out","w",stdout);
	scanf("%ld %ld",&n,&m);
	for (i=1; i<=n; i++)
		scanf("%d",&a[i]);
	for (i=1; i<=m; i++)
		scanf("%d",&b[i]);
	for (i=1; i<=n; i++)
		for (j=1; j<=m; j++)
		{
			if (a[i]!=b[j])
			{
				mt[i][j]=mt[i-1][j];
				if (mt[i][j]<mt[i][j-1])
					mt[i][j]=mt[i][j-1];
			}
			else mt[i][j]=mt[i-1][j-1]+1;
		}
	i=n;
	j=m;
	while (i!=0 || j!=0)
	{
		if (mt[i-1][j-1]==mt[i][j]-1)
		{
			h++;
			v[h]=a[i];
			i--;
			j--;
		}
		else if (mt[i-1][j]==mt[i][j])
				i--;
			 else j--;
	}
	printf("%ld\n",h);
	for (i=h; i>1; i--)
		printf("%d ",v[i]);
	printf("%d\n",v[1]);
	fclose(stdin);
	fclose(stdout);
	return 0;
}