#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;
}