#include <fstream>

using namespace std;

ifstream f("cmlsc.in");
ofstream g("cmlsc.out");
int n , m ,i , j , x , b[1050],c[1040],sol[1040];
int a[1000][1000];
int main()
{
    f >> n >> m ;
      for ( i = 1 ; i <= n ; i ++ )
        f >> b[i] ;
      for ( i = 1 ; i <= m ; i ++ )
         f >> c[i];
       for ( i = 1 ; i <= n ; i ++ )
        for ( j = 1 ; j <= m ; j ++ )
        if ( b[i] == c[j] )
             a[i][j]=a[i-1][j]+1;
          else
            a[i][j]=max(a[i-1][j],a[i][j-1]);
    i=n; j = m;
       while(a[i][j])
       {
           while ( a[i][j] == a[i-1][j] )
              i--;
         while ( a[i][j] == a[i][j-1] )
            j--;
           x++;
           sol[x]=b[i];
           i--;
           j--;
       }
        g << x <<'\n';
        for ( i = x ; i >= 1 ; i -- )
             g << sol[i]<<" " ;
    return 0;
}