#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;
 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])
            {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();
}