#include <fstream>
using namespace std;
ifstream fin("cmlsc.in");
ofstream fout("cmlsc.out");
int a[1025][1025],b[1025],c[1025],sub[1025];
int main()
{ 
	int n,m,i,j,x=0;

	fin>>n>>m;

	for(i=1;i<=n;i++)fin>>b[i];
	for(i=1;i<=m;i++)fin>>c[i];


for(i=1;i<=n;i++)
    for(j=1;j<=m;j++)
        {
            if(b[i]==c[j]) a[i][j]=a[i-1][j-1]+1;
            else a[i][j]=max(a[i-1][j], a[i][j-1]);
        }
	
i=n;j=m;

while(a[i][j]){
    while(a[i][j]==a[i-1][j])i--;
    while(a[i][j]==a[i][j-1])j--;

    sub[++x]=b[i];
    i--;j--;
    }
fout<<a[n][m]<<"\n";
for(i=x;i>=1;i--)fout<<sub[i]<<" ";
fin.close();
fout.close();
    return 0;
}