#include <fstream>
#define DMAX 1032
using namespace std;
ifstream fin("cmlsc.in");
ofstream fout("cmlsc.out");

int n, m;
int a[DMAX];
int b[DMAX];
int LCS[DMAX][DMAX];
char unde[DMAX][DMAX];
void citire();
void afisare();
void pd();
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]<<'\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();
}