#include <fstream>
#define DMAX 1032

using namespace std;
ifstream fin("cmlsc.in");
ofstream fout("cmlsc.out");
void citire();
void pd();
void afisare();
int a[DMAX],b[DMAX];
int n,m;
int lgmax[DMAX][DMAX];
char unde[DMAX][DMAX];
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])
            {
             lgmax[i][j]=1+lgmax[i+1][j+1];
             unde[i][j]='1';
            }
              else
              {
               if(lgmax[i+1][j]>lgmax[i][j+1])
                 {
                  lgmax[i][j]=lgmax[i+1][j];
                  unde[i][j]='2';
                 }
                 else
                 {
                  lgmax[i][j]=lgmax[i][j+1];
                  unde[i][j]='3';
                 }

              }
          }
}
void afisare()
{int i,j;
    fout<<lgmax[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';
    fin.close();
    fout.close();
}