#include <fstream>
#include <iostream>
using namespace std;

int s1[1069],s2[1069],m[1069][1069];


int main()
{   ifstream fin ("cmlsc.in");
    ofstream fout ("cmlsc.out");
    int N,M,i,j;
    fin>>M>>N;
    for (i=1;i<=M;i++)
    fin>>s2[i];
    for (i=1;i<=N;i++)
    fin>>s1[i];
    int p[1069],k=0;
    for (i=1;i<=N;i++)
    for (j=1;j<=M;j++)
    if (s1[i]==s2[j])
    m[i][j]=m[i-1][j-1]+1;
    else m[i][j]=max(m[i-1][j],m[i][j-1]);


    i=N;
    j=M;
    while (m[i][j])
    {while (m[i][j]==m[i][j-1]) j--;
     while (m[i][j]==m[i-1][j]) i--;
     p[++k]=s1[i];

    i--,j--;}
    fout<<m[N][M]<<"\n";
    for (i=k;i>0;i--)
    fout<<p[i]<<" ";
    return 0;
}