#include <fstream>
#include <iostream>
#include <string>
#include <vector>
#include <string>

#define min(a,b) ((a<b)?a:b)
#define max(a,b) ((a<b)?b:a)
#define abs(a) ((a<0)?-a:a)

#define INF 2147483647

using namespace std;

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

int n,m;

int *a,*b;

vector<int> LCS()
{
    int **c;
    c=new int*[n+1];
    for (int i=0; i<n+1; i++)
        c[i]=new int[m+1];

    for (int i=0; i<=n; i++)
        for (int j=0; j<=m; j++)
        {
            if (i*j==0)
                c[i][j]=0;
            else if (a[i]==b[j]) c[i][j]=c[i-1][j-1]+1;
            else c[i][j]=max(c[i-1][j],c[i][j-1]);
        }

    vector<int> rez;

    rez.push_back(c[n][m]);

    for (int i=n,j=m; i;)
    {
        if (a[i]==b[j])
        {
            rez.push_back(a[i]);
            i--;
            j--;
        }
        else if (c[i-1][j]<c[i][j-1]) j--;
        else i--;
    }

    return rez;
}

int main()
{
    fin>>n>>m;

    a=new int[n+1];
    b=new int[m+1];

    for (int i=1; i<=n; i++)
        fin>>a[i];

    for (int i=1; i<=m; i++)
        fin>>b[i];

    vector<int> sir=LCS();

    fout<<sir[0]<<'\n';
    for (int i=sir.size()-1; i; i--)
        fout<<sir[i]<<' ';

    return 0;
}