#include <fstream>
#define maxn 1030
using namespace std;
ifstream fin("cmlsc.in");
ofstream fout("cmlsc.out");
int m,n,a[maxn],b[maxn],d[maxn][maxn],s[maxn];
int main()
{
	int i=0, j=0, k=0;
	fin>>m>>n;
	for (i=1;i<=m;i++) 
		fin>>a[i];
	for (i=1;i<=n;i++) 
		fin>>b[i];
	for (i=1; i <= m; i++)
		for (j=1; j <= n; j++)
			if (a[i] == b[j]) 
				d[i][j] = d[i-1][j-1] + 1;
			else
				if (d[i-1][j] > d[i][j-1])
					d[i][j] = d[i-1][j];
				else
					d[i][j] = d[i][j-1];
	fout<<d[m][n]<<endl;
	i=m;
	j=n;
	while (d[i][j]!=0)
	{
		if (a[i]==b[j])
		{
			s[++k]=b[j];
			i--;
			j--;
		}
		else 
			if (d[i][j-1] == d[i][j])
				j--;
			else
				i--;
	}
	for (i=k; i > 0; --i) 
		fout<<s[i]<<" ";
	return 0;
}