#include <stdio.h>
long sir1[1025],sir2[1025],a[1025][1025],i,j,n,m,k,p[1025],l;
int main()
{
    freopen("cmlsc.in","r",stdin);
    freopen("cmlsc.out","w",stdout);
    scanf("%ld %ld",&n,&m);
    
    for(i=1;i<=n;i++)
    scanf("%ld",&sir1[i]);
    
    for(i=1;i<=m;i++)
    scanf("%ld",&sir2[i]);

    for(i=n;i>=1;i--)
    for(j=m;j>=1;j--)
    {
     if(sir1[i]==sir2[j])
     {
     k++;
     a[i][j]=a[i+1][j+1]+1;
     p[k]=i;
     }
     else if(a[i][j+1]<a[i+1][j])a[i][j]=a[i][j+1]+1;
     else a[i][j]=a[i+1][j]+1;
    }
    printf("%ld\n",k);
    i=0;
    for(i=k;i>=1;i--)
    {printf("%ld ",sir1[p[i]]);}
    return 0;  
}