#include <fstream>

using namespace std;
ifstream cin("cmlsc.in");
ofstream cout("cmlsc.out");
int v[1024][1024];
int a[1024];
int b[1024];
int c[1024];
int main()
{
    int n,m;
    cin>>n>>m;
    for(int i=1; i<=n; i++)
    {
        cin>>a[i];
    }
    for(int i=1; i<=m; i++)
    {
        cin>>b[i];
    }
    for(int i=1; i<=n; i++)
    {
        for(int j=1; j<=m; j++)
        {

            if(a[i]==b[j])
                v[i][j]=v[i-1][j-1]+1;
                else
               v[i][j]=max(v[i][j-1],max(v[i-1][j],v[i-1][j-1]));
        }
    }
    cout<<v[n][m]<<"\n";
    int l=v[n][m];
    int i=n;
    int j=m;
    while(v[i][j]!=0)
    {
        if(a[i]==b[j])
        {
            c[l]=a[i];
                i--;
                j--;
                l--;
        }
        else
        {
            if(v[i-1][j]>v[i][j-1])
              i--;
            else
              j--;
        }
    }
    for(int i=1;i<=v[n][m];i++)
        cout<<c[i]<<" ";
}