#include <stdio.h>
      
    #define maxim(a, b) ((a > b) ? a : b)  
    #define FOR(i, a, b) for (i = a; i <= b; ++i)  
    #define NMax 1024  
      
    int M, N, A[NMax], B[NMax], D[NMax][NMax], sir[NMax], bst;  
     
   int main(void)  
   {  
       int i, j;  
         
       freopen("cmlsc.in", "r", stdin);  
       freopen("cmlsc.out", "w", stdout);  
     
       scanf("%d %d", &M, &N);  
       FOR (i, 1, M)  
           scanf("%d", &A[i]);  
       FOR (i, 1, N)  
           scanf("%d", &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;  
     
       printf("%d\n", bst);  
       for (i = bst; i; --i)  
         printf("%d ", sir[i]);  
   
     return 0;  
  }