#include <fstream>
#define DMAX 1030

using namespace std;

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

int n, m;
int a[DMAX];
int b[DMAX];
int lgmax[DMAX][DMAX];
int unde[DMAX][DMAX];

int main()
{
    int i, j;

//citire

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

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

    for(i=n; i > 0; i--)
        for(j=m; j > 0; j--)
        {
            if(a[i] == b[j])
            {
                lgmax[i][j] = 1 + lgmax[i+1][j+1];
                unde[i][j] = 1;
            }
            else if(lgmax[i+1][j] > lgmax[i][j+1])
            {
                lgmax[i][j] = lgmax[i+1][j];
                unde[i][j] = 2;
            }
            else
            {
                lgmax[i][j] = lgmax[i][j+1];
                unde[i][j] = 3;
            }
        }

    fout<<lgmax[1][1]<<endl;

    i=1, j=1;

    while(i <= n && j <= m)
    {
        if(unde[i][j] == 1)
        {
            fout<<a[i]<<' ';
            i++, j++;
        }
        else if(unde[i][j] == 2) i++;
        else j++;
    }

    fout.close();
    return 0;
}