#include <stdio.h>   
#define max(a,b) ((a>b)?a:b) 
long sir1[1025],sir2[1025],a[1025][1025],i,j,n,m,k,v[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>0;i--)  
     for(j=m;j>0;j--)   
    {   
     if(sir1[i]==sir2[j])
        a[i][j]=a[i+1][j+1]+1;
          else a[i][j]=max(a[i+1][j],a[i][j+1]);
    }   
   /*
    for(i=1;i<=n;i++)  
    {  
    for(j=1;j<=m;j++)  
    printf("%ld",a[i][j]);  
    printf("\n");  
    }  */
    i=1;j=1;k=0;
    for (;i<=n&&j<=m;){
        if(sir1[i]==sir2[j])
        {v[++k]=sir1[i];++i;++j;}
        else if (a[i][j+1]<a[i+1][j])i++;
        else j++;
    }  
    printf("%ld\n",a[1][1]);
    for(i=1;i<=k;++i)
    printf("%ld ",v[i]);    
    printf("\n");
    return 0;     
}