#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();
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]<<endl;
    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++;


    }
}