#include<cstdio>
using namespace std;
#define maxim(a,b) ((a>b)?a:b)
int A[1100],B[1100],n,m,i,D[1100][1100],j,sir[1100],bst;
void read();void solve();
int main()
{
    read();
    solve();
    return 0;
}
void read()
{
    freopen("cmlsc.in","r",stdin);
    freopen("cmlsc.out","w",stdout);
    scanf("%d %d",&n,&m);
    for(i=1;i<=n;i++) scanf("%d",&A[i]);
    for(i=1;i<=m;i++) scanf("%d",&B[i]);
}
void solve()
{
    for(i=1;i<=n;i++)
    {
        for(j=1;j<=m;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 = n, j = m; 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]);
}