#include <iostream>
#include <fstream>
#include <algorithm>
using namespace std;
ifstream fin("cmlsc.in");
ofstream fout("cmlsc.out");
int c[1025][1025],a[1025],b[1025],v[1025],n,m;
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])
                c[i][j]=c[i-1][j-1]+1;
            else if(c[i][j-1]>=c[i-1][j])
                c[i][j]=c[i][j-1];
            else
                c[i][j]=c[i-1][j];
        }

    fout<<c[n][m]<<'\n';

    int i=n,j=m,q=1;

    while((i>=0 and j>=0) and c[i][j]!=0)
    {
        if(a[i]==b[j])
        {
            v[q]=a[i];
            q++;
            i--;
            j--;
        }
        else if(c[i-1][j]>c[i][j-1])i--;
        else j--;

    }
    for(int i=q-1; i>=1; i--)
        fout<<v[i]<<" ";
    return 0;
}