#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;  
}