#include <bits/stdc++.h>
using namespace std;
ifstream fin ("cmlsc.in");
ofstream fout ("cmlsc.out");
const short Nmax = 1025;
int dp[Nmax][Nmax] , n , m , a[Nmax] , b[Nmax];
void Rec(int i , int j)
{
    if(!i || !j)
        return;
    if(a[i] == b[j])
    {
        Rec(i - 1 , j - 1);
        fout << a[i] << " ";
    }
    else if(dp[i - 1][j] < dp[i][j - 1])
        Rec(i , j - 1);
    else Rec(i - 1 , j);
}
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])
                dp[i][j] = dp[i - 1][j - 1] + 1;
        else dp[i][j] = max(dp[i - 1][j] , dp[i][j - 1]);
    }
    fout << dp[n][m] << "\n";
    Rec(n , m);
    fin.close();
    fout.close();
    return 0;
}