#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("clmscs.in", "r", stdin);
freopen("clmscs.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; 
}