#include <fstream>
using namespace std;
ifstream in("cmlsc.in");
ofstream out("cmlsc.out");

int a[1025], b[1025], c[1025][1025], n,m,v[1025], k;

int main(){
	int i, j;
	in>>n>>m;
	for( i=1; i<=n; i++) in>>a[i];
	for( j=1; j<=m; j++) in>>b[j];
	for(i=1; i<=n; i++)
		for(j=1; j<=m; j++)
			if(a[i]==b[j]) c[i][j]=c[i-1][j-1]+1;
		else if(c[i-1][j]>=c[i][j-1]) c[i][j]=c[i-1][j];
			else c[i][j]=c[i][j-1];
	out<<c[n][m]<<endl;
	i=n;
	j=m;
	k=c[n][m];
	while( i and j){
		if(a[i]==b[j]){
			v[k--]=a[i];
			i--;
			j--;
		}
		else if(c[i-1][j]>=c[i][j-1])
			i--;
		else
			j--;
	}
	k=c[n][m];
	for(i=1; i<=k; i++)
		out<<v[i]<<" ";
	return 0;
}