/***************************************************
 * Author: Alexandru Palcuie
 * Country: Romania
 * Email: alex [dot] palcuie [at] gmail [dot] com
 * Website: http://palcu.blogspot.com/
 * Year: 2012
****************************************************/

#include <vector>
#include <list>
#include <map>
#include <set>
#include <deque>
#include <stack>
#include <queue>
#include <bitset>
#include <algorithm>
#include <functional>
#include <fstream>
#include <numeric>
#include <utility>
#include <sstream>
#include <iostream>
#include <iomanip>
#include <cstdio>
#include <cmath>
#include <cstdlib>
#include <ctime>
#include <iterator>
#include <cstring>

using namespace std;

//{Defines
#define NAME(n) #n
#define pr(x) db((x), (#x))
#define prv(v,n) dbv((v), (#v), (n))
#define prw(v) dbw((v), (#v))
#define ALL(c) (c).begin(), (c).end()
#define SORT(c) sort(ALL(c))
#define X first
#define Y second
#define pb push_back

//Constants
const int N = 1027;

//Structs

//Global Vars
int x, y, m[N][N];
int v[N], w[N];
int sol[N], sz;

//{Helpers
template <typename T>
inline void db(const T x, const char * name){
	cerr << name << " = " << x << '\n';
}
template <typename T> inline void dbv(const T * v, const char * name, int n){
	fprintf(stderr, "=== %s ===\n", name);
	for(int i=0; i<n; i++)
		cerr << v[i] << " ";
	cerr << '\n';
}
template <typename T> inline void dbs(T x){
	cerr << x << ' ';
}

template<typename T>
void dbw(const std::vector<T>& t, const char * name){
	fprintf(stderr, "=== %s ===\n", name);
	unsigned n = t.size();
	for(typename std::vector<T>::size_type i=0; i<n; ++i)
		std::cerr << t[i] << ' ';
	cerr << '\n';
}
//}

//Solve Functions
int main(){
	#ifndef ONLINE_JUDGE
	freopen("cmlsc.in","r",stdin);
	freopen("cmlsc.out","w",stdout);
	#endif

	int x, y;
	scanf("%d%d", &x, &y);

	int i,j;
	for(i=1; i<=x; i++) scanf("%d", &v[i]);
	for(i=1; i<=y; i++) scanf("%d", &w[i]);

	for(i=1; i<=x; i++)
		for(j=1; j<=y; j++)
			if(v[i] == w[j])
				m[i][j] = m[i-1][j-1] + 1;
			else
				m[i][j] = max(m[i-1][j], m[i][j-1]);

	printf("%d\n", m[x][y]);

	i=x, j=y;
	while(i && j){
		if(v[i] == w[j]){
			sol[sz++] = v[i];
			i--, j--;
		}
		else if (m[i-1][j] < m[i][j-1])
			j--;
		else
			i--;
	}
	for(i=sz-1; i>=0; i--)
		printf("%d ", sol[i]);

	return 0;
}