#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;

ifstream f("cmslc.in");
ofstream g("cmlsc.out");

int M, N, A[NMax], B[NMax], D[NMax][NMax], sir[NMax], bst;

int main()
{
    int i, j;
    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<<endl;
       for(i=bst;i;--i)
        g<<sir[i]<<" ";
        return 0;
}