#include<fstream.h>
int sir[1025],bst=0,c[1025][1025];
int maxim(int d,int e)
 {
  if(d>e)
   return d;
    else
     return e;
 }
void ver(int a[1025],int b[1025],int m,int n)
{ int i,j;
 for(i=1;i<=m;i++)
  for(j=1;j<=n;j++)   
    if (a[i] == b[j])   
      c[i][j] = 1 + c[i-1][j-1];   
       else  
             c[i][j] = maxim(c[i-1][j], c[i][j-1]);   
    i=m;
    j=n;
    while(i)   
    if (a[i] == b[j])   
      {sir[++bst] = a[i];
	--i;
	 --j;
	 }   
        else if (c[i-1][j] < c[i][j-1])   
            --j;   
        else  
            --i;   
    ofstream g("cmlsc.out");
    g<<bst<<"\n";  

    for (i = bst; i; --i)   
       g<<sir[i]<<" ";
}
int main()
{
int i,j,n,m,a[1024],b[1024];
ifstream f("cmlsc.in");
f>>n>>m;
for(i=1;i<=n;i++)
 f>>a[i];
for(j=1;j<=m;j++)
 f>>b[j];
  ver(a,b,n,m);
return 0;
}