#include <bits/stdc++.h>
#define NMAX 1030
using namespace std;
ifstream fin("cmlsc.in");
ofstream fout("cmlsc.out");
int a[NMAX],n;
int b[NMAX],m;
int lgmax[NMAX][NMAX];
int unde[NMAX][NMAX];
int main()
{int i,j;
fin>>n>>m;
for(i=1;i<=n;i++)
    fin>>a[i];
for(i=1;i<=m;i++)
    fin>>b[i];
//gata citirea
for(i=n;i>0;i--)
    for(j=m;j>0;j--)
        if(a[i]==b[j])
        {
         lgmax[i][j]=1+lgmax[i+1][j+1];
         unde[i][j]=1;
        }
        else //nu sunt egale
         if(lgmax[i+1][j]>lgmax[i][j+1])
         {
           lgmax[i][j]=  lgmax[i+1][j];
           unde[i][j]=2;
         }
         else
         {
           lgmax[i][j]=  lgmax[i][j+1];
           unde[i][j]=3;
         }
  fout<<lgmax[1][1]<<'\n';
  i=j=1;
  while(i<=n && j<=m)
    {
    if(unde[i][j]==1)
        {fout<<a[i]<<' ';i++;j++;}
        else
        if(unde[i][j]==2) i++;
        else
            j++;

    }

    return 0;
}