#include <cstdio> 
#include <cstring> 
 
 
using namespace std; 

 
#define MAX_N 1030 

 
int n, m; 
int d[MAX_N][MAX_N], A[MAX_N], B[MAX_N], R[MAX_N]; 

 
inline 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", &n, &m); 
     
 
    
for (int i = 1; i <= n; ++i) scanf ("%d", A + i); 
   
for (int i = 1; i <= m; ++i) scanf ("%d", B + i); 
    
for (int i = 1; i <= n; ++i)         
for (int j = 1; j <= m; ++j) 
           
if (A[i] == B[j]) 
               
d[i][j] = d[i - 1][j - 1] + 1; 
            
else
               
d[i][j] = MAX (d[i - 1][j], d[i][j - 1]); 
                
 
    
printf ("%d\n", d[n][m]); 
   
   
int pi = n, pj = m, k; 
    
 
    
for (k = 0; pi * pj > 0;) 
        
if (A[pi] == B[pj]) 
          
R[++k] = A[pi], --pi, --pj; 
        
else
            
if (d[pi - 1][pj] > d[pi][pj - 1]) --pi; 
                                          
else --pj; 
                                           
 
    
for (int i = k; i; --i) printf ("%d ", R[i]); 
        
return 0; 
}