#include<fstream.h>
ifstream f("cmlsc.in");
ofstream g("cmlsc.out");
int a[1026],b[1026],i,j,M[1026][1026],n,m; 
int main() 
{     
	f>>m>>n;    
	for (i=1;i<=m;i++)       
		f>>a[i]; 
	for (i=1;i<=n;i++)        
		f>>b[i]; 
	for (i=m;i>=1;i--)    
		for (j=n;j>=1;j--) if (a[i]==b[j]) M[i][j]=1+M[i+1][j+1]; 
								else if (M[i][j+1]>M[i+1][j]) M[i][j]=M[i][j+1]; 
										else M[i][j]=M[i+1][j]; 
	g<<M[1][1]<<'\n';
	i=j=1; 
	while (M[i][j]!=0)        
		if (a[i]==b[j])    
			{g<<a[i]<<' ';
			i++; j++;}
			else if (M[i][j+1]>M[i+1][j]) j++; 
					else i++; 
	g<<'\n';
	f.close(); g.close();
	return 0; 
}