#include <fstream>
#define DMAX 1032
using namespace std;
ifstream fin("cmlsc.in");
ofstream fout("cmlsc.out");
int n,m,a[DMAX],b[DMAX],LCS[DMAX][DMAX];
char unde[DMAX][DMAX];
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';

}
int main()
{
    citire();
    pd();
    afisare();

    return 0;
}