#include <iostream>
#include <fstream>
using namespace std;
ifstream fin("cmlsc.in");
ofstream fout("cmlsc.out");
int n,m,v1[1025],v2[1025],a[1025][1025],i,j;
int main()
{
    fin>>n>>m;
    for (i=1;i<=n;i++)
        fin>>v1[i];
    for (i=1;i<=m;i++)
        fin>>v2[i];
    for (i=1;i<=n;i++)
        for (j=1;j<=m;j++)
            if (v1[i]==v2[j])
                a[i][j]=1+a[i-1][j-1];
                else a[i][j]=max(a[i-1][j],a[i][j-1]);
    fout<<a[n][m]<<'\n';
    for (i=a[n][m];i>=1;i--)
        fout<<v1[i]<<' ';
    return 0;
}