//cel mai lung subsir comun
#include<iostream>
#include<fstream>
using namespace std;
ifstream in("cmlsc.in");
ofstream out("cmlsc.out");

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

int main(){
	int i,j,sol[1025],k;
	in>>n>>m;
	for(i=1; i<=n; i++)
		in>>a[i];
	for(i=1; i<=m; i++)
		in>>b[i];
	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][j-1]>=c[i-1][j])
					c[i][j]=c[i][j-1];
				else
					c[i][j]=c[i-1][j];
			}
	out<<c[n][m]<<endl;
	i=n;
	j=m;
	k=c[n][m];
	while(i && j){
		if(a[i]==b[j]){
			sol[k]=a[i];
			k--;
			i--;
			j--;
		}
		else
			if(c[i][j-1]>=c[i-1][j])
				j--;
			else
				i--;
	}
	for(i=1; i<=c[n][m]; i++)
		out<<sol[i]<<" ";
	return 0;
}