#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; 
}