#include <iostream>
#include<fstream>
#define DMAX 1032
using namespace std;
ifstream fin("cmlsc.in");;
ofstream fout("cmlsc.out");
void citire();
void pd();
void afisare();
int n, m;
int a[DMAX];
int b[DMAX];
int LCS[DMAX][DMAX];
char unde[DMAX][DMAX];
int main()
{
    citire();
    pd();
    afisare();
    return 0;
}
void citire()
{
    fin>>n>>m;
    for(int i=1; i<=n;i++)
    {
        fin>>a[i];
    }
    for(int i =1; i<=m;i++)
    {
        fin>>b[i];
    }
}
void pd()
{
    for(int i=n;i>0;i--)
    {
        for(int j=m;j>0;j--)
        {
            if(a[i]==b[j])
            {
                LCS[i][j]=1+LCS[i+1][j+1];
                unde[i][j]='1';
            }
            else
            {
                if(LCS[i+1][j]>LCS[i][j+1])
                {
                    LCS[i][j]=LCS[i+1][j];
                    unde[i][j]='2';
                }
                else
                {
                    LCS[i][j]=LCS[i][j+1];
                    unde[i][j]='3';
                }
            }
        }
    }
}
void afisare()
{
    fout<<LCS[1][1]<<'\n';
    int i=1;
    int 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<<'\n';
    fout.close();
}