#include<stdio.h>
using namespace std;
int a[1025],b[1025], matrice[1025][1025];
int n,m;
 
void afis(int i,int j)
{
    if(i>0&&j>0)
    if (a[i]==b[j])
    {afis(i-1,j-1);
    printf("%d ",a[i]);
    }
    else
        if (matrice[i-1][j]>matrice[i][j-1])
            afis(i-1,j);
            else afis(i,j-1);
 
}
int max(int a,int b)
{
    if (a>b) return a;
    return  b;
}
int main()
{
    int i,j;
    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(j=1;j<=m;j++)
      scanf("%d ",&b[j]);
    for(i=1;i<=n;i++)
        for(j=1;j<=m;j++)
            if(a[i]==b[j])
                matrice[i][j]=matrice[i-1][j-1]+1;
                else
                    matrice[i][j]=max(matrice[i-1][j],matrice[i][j-1]);
                 
            printf("%d\n",matrice[n][m]);
             
            afis(n,m);      
            return 0;
     
     
 
}