#include <cstdio>
#define max_l 1024
using namespace std;
int n,m,a[max_l],b[max_l];
int lcs[max_l][max_l];
int s[max_l],bst;

int max(int x,int y)
{
    if(x>y)return x;
  return y;
}

int main(void)
{
     freopen("cmlsc.in","r",stdin);
     freopen("cmlsc.out","w",stdout);
     scanf("%d%d",&n,&m);
     int i=1,j;
     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])
            lcs[i][j]=lcs[i-1][j-1]+1;
         else          
            lcs[i][j]=max(lcs[i-1][j],lcs[i][j-1]);
     i=m;j=n;
     while(i&&j)
      {
       if(a[i]==b[j])
         {
          s[++bst]=a[i];
           --i;--j;
         }
       else 
         if(lcs[i-1][j]>lcs[i][j-1])
              i--;
       else
        j--;
       }
       printf("%d\n",bst);
       for(i=bst;i>0;i--)
       printf("%d ",s[i]);
}