#include <bits/stdc++.h>
using namespace std;
ifstream fin("cmlsc.in");
ofstream fout("cmlsc.out");
int a[1024],b[1024],l[1024][1024],r[1024];
int main()
{
    int n,m,i,j,rez;
    fin>>n>>m;
    for(int i=1;i<=n;i++)
        fin>>a[i];
    for(int j=1;j<=m;j++)
        fin>>b[j];
    for(int i=1;i<=n;i++)
        for(int j=1;j<=m;j++)
    {
        if(a[i]==b[j]) l[i][j]=l[i-1][j-1]+1;
        else l[i][j]=max(l[i-1][j],l[i][j-1]);
    }
    rez=l[n][m];
    fout<<rez<<endl;
   i=n;
   j=m;
   while(rez)
   {
       if(a[i]==b[j])
       {
           r[rez]=a[i];
           i--;
           j--;
           rez--;
       }else if(l[i-1][j]>l[i][j-1]) i--;
       else j--;
   }
   rez=l[n][m];
   for(int i=1;i<=rez;i++) fout<<r[i]<<" ";
}