#include <fstream>
#include <algorithm>

using namespace std;

ifstream f("cmlsc.in");
ofstream g("cmlsc.out");

#define maxim(a, b) ((a > b) ? a : b)
#define NMax 1024

int m, n, a[NMax], b[NMax], d[NMax][NMax], sir[NMax], bst;

int main()
{
    int i, j;

    f>>m>>n;
    for (int i=1; i<=m; i++) f>>a[i];
    for (int i=1; i<=n; i++) f>>b[i];

    for (int i=1; i<=m; i++)
      for (int j=1; j<=n; j++)
        if (a[i]==b[j]) d[i][j]=1+d[i-1][j-1];
          else d[i][j]=max(d[i-1][j], d[i][j-1]);

    for (i=m, j=n; i; )
      if (a[i]==b[j])
      {
          sir[++bst]=a[i]; --i; --j;
      }
      else if (d[i-1][j] < d[i][j-1]) --j;
             else --i;

    g<<bst<<'\n';
    for (i = bst; i; --i) g<<sir[i]<<' ';

    return 0;
}