#include <iostream>
#include <fstream>

using namespace std;

ifstream fin("cmlsc.in");
ofstream fout("cmlsc.out");
const int maxn=1030;

int m, n, a[maxn], b[maxn], cmlsc[maxn][maxn], maxim[maxn];

void drum(int i ,int j){
	if(i==0 || j==0) return;
	if( a[i] == b[j]) {
		drum(i - 1, j - 1);
		fout << a[i] << ' ';
	} else if(cmlsc[i - 1][j] > cmlsc[i][j - 1]) {
		drum(i - 1, j);
	} else {
		drum(i, j - 1);
	}
}


int main(){
	fin >> m >> n;
	for(int i=1 ; i<=m; i++){
		fin >> a[i];
	}
	for(int j=1; j<=n; j++){
		fin >> b[j];
	}
	for(int i=1 ; i<=m; i++){
			for(int j=1; j<=n; j++){
				if(a[i]==b[j]) cmlsc[i][j]=cmlsc[i-1][j-1]+1;
				else cmlsc[i][j]=max(cmlsc[i-1][j], cmlsc[i][j-1]);
			}
	}
	fout<< cmlsc[m][n]<<'\n';
	drum(m, n);


return 0;
}