#include <fstream>
#define DMAX 1050

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

int n,m;
int a[DMAX],b[DMAX],LCS[DMAX][DMAX];
char unde[DMAX][DMAX];

void citire();
void pd();
void afisare();

int main()
{
 citire();
 pd();
 afisare();
 return 0;
}
void citire()
{
 int i;
 fin>>n>>m;
 for (i=1;i<=n;i++)
     fin>>a[i];
 for (i=1;i<=n;i++)
     fin>>b[i];
}
void pd()
{
 int i,j;
 for (i=n;i>0;i--)
    for (j=m;j>0;j--)
      if (a[i]==b[j])
         {
          LCS[i][j]=1+LCS[i+1][j+1];
          unde[i][j]='1';
         }
      else
      if (LCS[i+1][j]>LCS[i][j+1])
          {
           LCS[i][j]=LCS[i+1][j];
           unde[i][j]='2';
          }
          else
          {
           LCS[i][j]=LCS[i][j+1];
           unde[i][j]='3';
          }
}
void afisare()
{
 int i,j;
 fout<<LCS[1][1]<<'\n';
 i=1;
 j=1;
 while (i<=n&&j<=m)
         {
          if (unde[i][j]=='1')
            {
             fout<<a[i]<<' ';
             i++;
             j++;
            }
           else if (unde[i][j]=='2')
                   i++;
            else
            j++;
         }
 fout<<'\n';
 fout.close();
}