#include <stdio.h>
#define maxim(a, b) ((a > b) ? a : b)
int M, N, A[1024], B[1024], D[1024][1024], sir[1024], bst;
int main()
{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>=1;--i)
  printf("%d ", sir[i]);
return 0;
}