#include <bits/stdc++.h>
#define nmax 1032
using namespace std;

ifstream fin("cmlsc.in");
ofstream fout("cmlsc.out");
int n,m,a[nmax],b[nmax],LCS[nmax][nmax];
char unde[nmax][nmax];
void citire();
void pd();
void afisare();
int main()
{
    citire();
    pd();
    afisare();
    return 0;
}
void citire()
{
    int i,j;
    fin >> n >> m;
    for(i=1;i<=n;i++)
        fin >> a[i];
    for(j=1;j<=m;j++)
        fin >> b[j];

}
void pd()
{
    int i,j;
    for(i=n;i>0;i--)
    {
        for(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()
{
    int i,j;
    fout << LCS[1][1] << '\n';
    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 << '\n';
    fout.close();
}