#include<bits/stdc++.h>
 
using namespace std;
 
int n,m,A[1030],B[1030],rs[1030], D[1030][1030],i,j,x;
    ifstream in("cmlsc.in");
    ofstream out("cmlsc.out");
int main()
{
 
    in>>m>>n;
     
    for(i=1;i<=m;i++)
      in>>A[i];
    for(i=1;i<=n;i++)
      in>>B[i];
       
    for(i=1;i<=m;i++)
      for(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]);
        
       out<<D[m][n]<<"\n"; 
     
    for(i=m,j=n;i && j;)
      if(A[i]==B[j]) {
      rs[++x]=A[i];
      i--;
      j--;}
      else
       
        if(D[i-1][j]<D[i][j-1])
          j--;
        else i--;
        out<<rs[x];
    for(i=x-1;i;i--)
     out<<" "<<rs[i];
        
        return 0;
     
}