#include<fstream>
using namespace std;
ifstream fin("cmlsc.in");
ofstream fout("cmlsc.out");
int a[1050][1050],n,m,i,k,OK,j,w[1050],v[1050],rez[1050];
int main()
{
	fin>>n>>m;
	for(i=1;i<=n;i++)
		fin>>v[i];
	for(i=1;i<=m;i++)
		fin>>w[i];
	for(i=1;i<=n;i++)
		for(j=1;j<=m;j++)
			if(v[i]==w[j])
				a[i][j]=a[i-1][j-1]+1;
			else
				a[i][j]=max(a[i-1][j],a[i][j-1]);
	fout<<a[n][m]<<"\n";
	OK=1;
	i=n;j=m;
	while(a[i][j])
	{
		if(v[i]==w[j])
		{
			rez[++k]=v[i];
			i--;
			j--;
		}
		else
		{
			if(a[i-1][j]>a[i][j-1])
				i--;
			else
				j--;
		}
	}
	for(i=k;i>0;i--)
		fout<<rez[i]<<" ";
	return 0;
}