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