#include <bits/stdc++.h>
using namespace std;

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

int a[1024], b[1024], n, m;
int v[1025][1025], r;

int main()
{
	fin>>n>>m;
	for (int i=1; i<=n; i++)
	{
		fin>>a[i];
	}
	for (int i=1; i<=m; i++)
	{
		fin>>b[i];
	}
	for (int i=n; i>=1; i--)
	{
		for (int j=m; j>=1; j--)
		{
			if (a[i]==b[j])
			{
				v[i][j]=v[i+1][j+1]+1;
			}
			else
			{
				v[i][j]=max(v[i+1][j], v[i][j+1]);
			}
		}
	}
	int l=v[1][1], x=1, y=1, xf, yf;
	fout<<l<<endl;
	while (l>0)
	{
		int maxi=0;
		for (int i=x; i<=n; i++)
		{
			for (int j=y; j<=m; j++)
			{
				if (v[i][j]==l and a[i]==b[j])
				{
					if (a[i]>maxi)
					{
						maxi=a[i];
						xf=i;
						yf=j;
					}
				}
			}
		}
		x=xf+1;
		y=yf+1;
		fout<<maxi<<" ";
		l--;
	}


	return 0;
}