#include <fstream>
#define DMAX 1040
using namespace std;
ifstream fin ("cmlsc.in");
ofstream fout ("cmlsc.out");
int LCS[DMAX][DMAX];
int n,m;
int a[DMAX];
int b[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];
    i=1; j=1;
     fout<<'\n';
    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';
}