#include <bits/stdc++.h>

#define f first
#define s second
#define M 1234567

using namespace std;

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

int dp[1030][1030], n, m, a[1030], b[1030];

void ct()
{
    fin >> n >> m;
    for(int i = 1; i <= n; i++)
        fin >> a[i];
    for(int i = 1; i <= m; i++)
        fin >> b[i];
}

void dinamica()
{
    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';
}

void backt()
{
    int prevj = 1;
    for(int i = 1; i <= n; i++)
    {
        for(int j = prevj; j <= m; j++)
        {
            if(a[i] == b[j])
            {
                fout << a[i] << ' ';
                prevj = j + 1;
                break;
            }
        }
    }
}

int main()
{
    ct();
    dinamica();
    backt();

    return 0;
}