#include <iostream>
#include <fstream>
#define nm 1025
using namespace std;

ifstream fin("cmlsc.in");
ofstream fout("cmlsc.out");

int n,m,a[nm],b[nm],lg[nm][nm],d[nm][nm];

void scrie(int i , int j )
{
    if(i>0 && j>0)
    {
        if(d[i][j]==1)
        {
            scrie(i-1,j-1);
            fout<<a[i]<<' ';
        }
        else
            if(d[i][j]==2)
            scrie(i-1,j);
            else
                scrie(i,j-1);
    }
}


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];
   for(i=1;i<=n;i++)
      for(j=1;j<=m;j++)
         if(a[i]==b[j])
        {
          lg[i][j]=lg[i-1][j-1]+1;
          d[i][j]=1;
        }
        else
            if(lg[i-1][j]>lg[i][j-2])
        {
            lg[i][j]=lg[i-1][j];
            d[i][j]=2;

        }
        else
        {
            lg[i][j]=lg[i][j-1];
            d[i][j]=3;
        }
    fout<<lg[n][m]<<'\n';
    scrie(n,m);
}