#include <fstream>
#define DMAX 1032

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

int n, m;
int a[DMAX];
int b[DMAX];
int 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; //n pt a, m pt b
  for (i=1; i<=n; i++)
      fin>>a[i];
  for (i=1; i<=m; 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]) //cazul I
             {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();
}