#include<fstream>
#include<string.h>
#include<ctype.h>
#include<iostream>
#include<algorithm>
#include<map>
#include<unordered_map>
#include<array>
#include<deque>
#include<unordered_set>
#include<set>
#include<math.h>
using namespace std;
int n, m,i,j,dp[1050][1050],v1[1050],v2[1050],rez[1050],nr;
int main()
{
	//ifstream f("file.in");
	//ofstream g("file.out");
	ifstream f("cmlsc.in");
	ofstream g("cmlsc.out");
	f >> m >> n;
	for (i = 1; i <= m; i++)
		f >> v1[i];
	for (i = 1; i <= n; i++)
		f >> v2[i];
	for (i = 1; i <= m; i++)
		for (j = 1; j <= n; j++)
			if (v1[i] == v2[j])
				dp[i][j] = 1 + dp[i - 1][j - 1];
			else
				dp[i][j] = max(dp[i - 1][j], dp[i][j - 1]);
	i = m;
	j = n;
	nr = 0;
	while (i != 0)
	{
		if (v1[i] == v2[j])
		{
			rez[++nr] = v1[i];
			--i;
			--j;
		}
		else
			if (dp[i - 1][j] < dp[i][j - 1])
				--j;
			else
				--i;
	}
	g << nr << "\n";
	for (i = nr; i >= 1; --i)
		g << rez[i] << " ";
	return 0;
}