#include <fstream>
#include <iostream>
#include <vector>
using namespace std;

ifstream in("cmlsc.in");
ofstream out("cmlsc.out");

int c[1025][1025],i,j,n,m,a[1025],b[1025],maxn=32000;
vector<int> buf;

int maxim(int x, int y)
{
	if(c[x-1][y] > c[x][y-1])
		return c[x-1][y];
	else
		return c[x][y-1];
}

int main()
{
	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])
			{
				if(i==1 || j==1)
					c[i][j] = 1;
				else
					c[i][j] = c[i-1][j-1]+1;
			}
			else
			{
				c[i][j] = c[i-1][j];
				if(c[i][j] < c[i][j-1])
					c[i][j] = c[i][j-1];
			}

	out<<c[n][m]<<'\n';
	
	maxn = c[n][m];
	i=n;j=m;
	while(i && j )
		{if(a[i]==b[j])
			buf.push_back(a[i]), i--, j--;
		else if(c[i][j-1] > c[i-1][j])
			j--;
		else
			i--;}
	for(i=buf.size()-1; i>=0; i--)
		out<<buf[i]<<' ';	
	return 0;
}