#include <stdio.h>  
    #define maxim(a, b) ((a > b) ? a : b)  
   
      
    int M, N, A[1025], B[1025], D[1025][1025], sir[1025], 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;i<=M;i++)  
           scanf("%d", &A[i]);  
       for (i=1;i<=N;i++)  
           scanf("%d", &B[i]);  
     
       for (i=1;i<=M;i++)  
           for  (j=1;j<=N;j++)  
              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;  
  }