#include <fstream>

#define maxim(a,b) ((a>b)? a : b)
#define For(i, a, b) for (i = a; i <= b; ++i)
#define NMax 1024
using namespace std;
int M, N, A[NMax], B[NMax], D[NMax][NMax], sir[NMax], bst;

int main()
{
    int i, j;
    ifstream f("cmlsc.in");
    ofstream g("cmlsc.out");
    
    f>>M>>N;
    For(i, 1, M)
          f>>A[i];
    For(i, 1, N)
          f>>B[i];
          
    For(i, 1, M)
       For(j, 1, N)
         if (A[i] == B[j])
            D[i][j] = 1 + D[i-1][j-1];
         else
            D[i][j] = maxim(D[i-1][j], D[i][j-1]);      
    
    for(i=M, j=N; i;)
      if(A[i] == B[j])
              sir[++bst] = A[i], --i, --j;
       else if (D[i-1][j] < D[i][j-1])
            --j;
       else 
            --i; 
    
    g<<bst<<"\n";
    for(i=bst; i; --i)
   g<<sir[i]<<' ';
   f.close(); g.close();
}