#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()
{
    fout<<LCS[1][1]<<'\n';
    int 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';
}