#include<stdio.h>

int v[1030][1030],a[1030],b[1030],sol[1030],i,j,n,m,k;

int main()
{
	freopen("cmlsc.in","r",stdin);
	freopen("cmlsc.out","w",stdout);
	
	scanf("%d %d",&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])
			{
				v[i][j]=v[i-1][j-1]+1;
				if(v[i][j]>k)
					sol[++k]=a[i];
			}
			else if(v[i][j-1]>v[i-1][j]) v[i][j]=v[i][j-1];
			else v[i][j]=v[i-1][j];
		}
		
	
	printf("%d\n",k);
	for(i=1;i<=k;i++)
		printf("%d ",sol[i]);
	
	return 0;
}