#include <bits/stdc++.h>
using namespace std;
ifstream fin("cmlsc.in");
ofstream fout("cmlsc.out");
int n,m,sol[1025][1025],a[1025],b[1025],vec[1025],k;
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])
                sol[i][j]=sol[i-1][j-1]+1;
            else if(sol[i-1][j]>sol[i][j-1])
                sol[i][j]=sol[i-1][j];
            else
                sol[i][j]=sol[i][j-1];}

     for(int i=n, j=m; i>0; )
        if(a[i]==b[j]){
            vec[++k]=a[i];
            i--;
            j--;}
        else if(sol[i][j-1]>sol[i-1][j])
            j--;
        else
            i--;

    fout<<k<<'\n';
    for(int i=k; i>0; i--)
        fout<<vec[i]<<" ";
    return 0;
}