#include <bits/stdc++.h>
#define N 1030
using namespace std;

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

int na,nb;
int a[N],b[N];
int t[N][N];
int sir[N]; int nsir;

int main()
{   int i,j;
    fin>>na>>nb;
    for (i=1;i<=na;i++) fin>>a[i];
    for (i=1;i<=nb;i++) fin>>b[i];
    fin.close();

    for (i=1;i<=na;i++)
        for (j=1;j<=nb;j++)
             if (a[i]==b[j]) t[i][j]=t[i-1][j-1]+1;
             else t[i][j]=max(t[i-1][j],t[i][j-1]);

    fout<<t[na][nb]<<"\n";

    for (i=na,j=nb;i;)
       if (a[i]==b[j]) { sir[++nsir]=a[i]; i--; j--; }
       else if (t[i-1][j]<t[i][j-1]) j--;
            else i--;

    for (i=nsir;i>=1;i--) fout<<sir[i]<<" ";
    fout<<"\n";

    return 0;
}