#include<stdio.h>
int a[1100],b[1100],d[1100][1100],i,j,n,m,c[1100];
int main()
{
	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(j=1;j<=n;j++)
			if(a[i]==b[j])
				d[i][j]=1+d[i-1][j-1];
			else 
				if(d[i][j-1]>d[i-1][j])
					d[i][j]=d[i][j-1];
				else 
					d[i][j]=d[i-1][j];
	printf("%d\n",d[m][n]);
	i=m;
	j=n;
	while(i&&j)
		if(a[i]==b[j])
		{
			c[++c[0]]=a[i];
			i--;
			j--;
		}
		else 
			if(d[i][j-1]<d[i-1][j])
				i--;
			else
				j--;			
	for(i=c[0];i;i--)
		printf("%d ",c[i]);
	return 0;
}