#include <bits/stdc++.h>

using namespace std;
ofstream fout("cmlsc.out");

const int Nmax = 1030;

int n, m;
int nsol;
int a[Nmax];
int b[Nmax];
int v[Nmax*Nmax];int dp[Nmax][Nmax];

void Read()
{
    int i;
    ifstream fin("cmlsc.in");
    fin >> n >> m;
    for(i = 1; i <= n; i++)
        fin >> a[i];
    for(i = 1; i<= m; i++)
        fin >> b[i];
    fin.close();
}

void LCS()
{
    int i, j;
    for(i = 1; i <= n; i++)
         for(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 Solve()
{
    LCS();
    int i, j;
    i = n; j = m;
    while(i > 0 && j > 0)
    {
        if(a[i] == b[j])
        {
            v[++nsol] = a[i];
            i--; j--;
        }
        else if(dp[i - 1][j] > dp[i][j - 1]) i--;
        else j--;
    }
    for(i = nsol; i >= 1; i--)
        fout << v[i] << " ";
    fout << "\n";
    fout.close();
}
int main()
{
    Read();
    Solve();
    return 0;
}