#include <fstream>  
    using namespace std;
    
    short int a[1024],b[1024],x[1024],l[1024][1024],i,j,n,m,k;  
      
      
    int main()  
    {  
     ifstream fin("cmlsc.in");  
     fin>>n>>m;  
     for(i=1;i<=n;i++)  
     fin>>a[i];  
    for(i=1;i<=m;i++)  
     fin>>b[i];  
    fin.close();  
     
    for(i=1;i<=n;i++)  
     for(j=1;j<=m;j++)  
      if(a[i]==b[j])  
       l[i][j]=l[i-1][j-1]+1;  
      else  
       if(l[i-1][j]>l[i][j-1])  
       l[i][j]=l[i-1][j];  
       else  
        l[i][j]=l[i][j-1];  
     
    k=l[n][m];  
    i=n; j=m;  
    while(k!=0)  
     if(a[i]==b[j])  
     {  
      x[k]=a[i];  
      k--; i--; j--;  
     }  
     else  
      if(l[i][j]==l[i][j-1])  
       j--;  
      else  
       i--;  
     
    ofstream fout("cmlsc.out");  
    fout<<l[n][m]<<'\n';  
    for(i=1;i<=l[n][m];i++)  
     fout<<x[i]<<" ";  
     
    return 0;  
   }