#include<fstream.h>
int i,j,n,m,s,sl[1025],a[1025],b[1025],v[1025][1025];
ifstream fin("cmlsc.in");
ofstream fout("cmlsc.out");
void citire(){
	fin>>n>>m;
	for(i=1;i<=n;i++)
		fin>>a[i];
	for(i=1;i<=m;i++)
		fin>>b[i];
}
int max(int a,int b){
	return (a>b)?a:b;
}
void din(){
	for(i=1;i<=n;i++)
		for(j=1;j<=m;j++)
			if(a[i]==b[j])
				v[i][j]=1+v[i-1][j-1];
			else
			   v[i][j]=max(v[i-1][j],v[i][j-1]);
	i=n;
	j=m;
	while(i>0&&j>0)
		if(a[i]==b[j]){
			 sl[++s]=a[i];
			 i--;
			 j--;
		}
		else
		   if(v[i-1][j]>v[i][j-1])
			   i--;
		else
		   j--;
	fout<<v[n][m]<<'\n';
	for(i=s;i>=1;i--)
		fout<<sl[i]<<" ";
}
int main(){
	 citire();
	 din();
    return 0;   
}