#include <fstream>

using namespace std;
ifstream f("cmlsc.in");
ofstream g("cmlsc.out");
int a[1030],b[1030],c[1030][1030],n,m,i,j;
void drum(int i, int j)
{
    if(i>0&&j>0){
        if(a[i]==b[j])
           {
               drum(i-1,j-1);
                g<<a[i]<<" ";
           }
        else
        {
            if(c[i-1][j]>c[i][j-1])
                drum(i-1,j);
            else drum (i,j-1);
        }
    }
}

int main()
{
    f>>n>>m;
    for(i=1;i<=n;++i)
        f>>a[i];
    for(j=1;j<=m;++j)
        f>>b[j];
    for(i=1;i<=n;++i)
    {
        for(j=1;j<=m;++j)
        {
            if(a[i]==b[j])
            {
                c[i][j]=c[i-1][j-1]+1;
            }
            else c[i][j]=max(c[i-1][j], c[i][j-1]);
        }
    }
    g<<c[n][m]<<endl;
    drum(n,m);
    return 0;
}