#include <iostream>

#include<fstream>

using namespace std;

#define maxim(a,b) ((a>b) ? a : b)

ifstream fin("cmlsc.in");

ofstream fout("cmlsc.out");



int n,m,a[1005],b[1005],d[1005][1005],sir[1005],br;

int main()

{

    fin>>n>>m;

    for(int i=1; i<=n; ++i)

        fin>>a[i];

    for(int i=1; i<=m; ++i)

    {

        fin>>b[i];

    }

    for(int i=1; i<=n; ++i)

    {

        for(int j=1; j<=m; ++j)

        {

            if(a[i]==b[j])

            {

                d[i][j]=1+d[i-1][j-1];

            }

            else

                d[i][j]=maxim(d[i-1][j],d[i][j-1]);

        }

    }

    for(int i=n; int j=m; i)

    {

        if(a[i]==b[j])

        {

            br++;

            sir[br]=a[i],--i,--j;

        }

        else

        {

            if(d[i-1][j]<d[i][j-1])

                --j;

            else

                --i;

        }

    }

   fout<<br<<endl;

    for(int i=br; i>=1; i--)

        fout<<sir[i]<<" ";







    return 0;

}