#include<iostream>
#include<fstream>
#define max(a,b) (a>b)? a:b
using namespace std;
int a[1025],b[1025],c[1025][1025],n,m,sol[1025],k;
    ofstream fout("cmlsc.out");
    ifstream fin("cmlsc.in");
void afisare(int i,int j)
{
 
    k=c[n][m];
    while(k>0)
    { 
       while(a[i]!=b[j])
          if (c[i-1][j]>c[i][j-1]) i--; else j--;
     
 
     sol[k]=a[i];
     i--;j--;
     k--;
     
    }
    k=c[n][m];
for(i=1;i<=k;i++)
  fout<<sol[i]<<" ";
  fout.close();
}
 
int main()
{
 
 
int i,j;
    fin>>n>>m;
    for(i=1;i<=n;++i)
    fin>>a[i];
     for(j=1;j<=m;++j)
     fin>>b[j];
    for(i=1;i<=n;++i)
 
    for(j=1;j<=m;++j)
     if(a[i]==b[j])   c[i][j]=c[i-1][j-1]+1;
     else
     c[i][j]=max(c[i][j-1],c[i-1][j]);
 
fout<<c[n][m]<<"\n";
afisare(n,m);
return 0;}