#include <fstream>
#define DMAX 1030

using namespace std;
ifstream fin("cmlsc.in");
ofstream fout("cmlsc.out");
int a[DMAX],b[DMAX];
int n,m;
int lgmax[DMAX][DMAX];
int unde[DMAX][DMAX];
int main()
{int i,j;
    //citire
    fin>>n>>m;
    for(i=1;i<=n;i++)
        fin>>a[i];
    for(i=1;i<=m;i++)
        fin>>b[i];
    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;
                 }

              }
           }
    //afisare
    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';
    fout.close();
    return 0;
}