#include <iostream>
#include <fstream>

using namespace std;

int L1, L2, i, j;

int A[1030], B[1030];

int D[1030][1030];

int REZ[1030];

int max(int a, int b){
    return a > b ? a : b;}

int main(){

    freopen("cmlsc.in", "r", stdin);
    freopen("cmlsc.out", "w", stdout);
     scanf("%d %d", &L1, &L2);
      for(i=1;i<=L1;++i)
        scanf("%d", &A[i]);

          for(i=1;i<=L2;++i)
             scanf("%d", &B[i]);
               //D[0][0] = 0;

               /*    for(i=1;i<=L1;++i)
                cout<<A[i]<<" ";
                 cout<<"\n";
                   for(i=1;i<=L2;++i)
                        cout<<B[i]<<" ";
                         cout<<"\n";*/

                          for(i=1;i<=L1;++i)
                               for(j=1;j<=L2;++j)
                                         if(A[i] == B[j])
                                                   {
                                                            D[i][j] = 1 + D[i-1][j-1];
                                                                       }
                                                                        else
                                                                    D[i][j] = max(D[i-1][j], D[i][j-1]);
   int ok = 0, lmax = 0;
     /*for(i=1;i<=L1;++i)
      for(j=1;j<=L2;++j)
       {
            if(D[i][j] > ok && A[i] == B[j])
                    {
                         ok = D[i][j];
                        REZ[++lmax] = A[i];++i;
                        j=L2;
 }         }*/
 for(i=L1;j=L2;i;)
    if(A[i] == B[j])
    {
        REZ[++lmax] = A[i];
        --i,--j;
    }
    else if(D[i-1][j] < D[i][j-1])
        --j;
    else
        --i;
  cout<<lmax<<"\n";    for(i=lmax;i>=1;--i)        cout<<REZ[i]<<" ";

  return 0;}