#include <bits/stdc++.h>
using namespace std;
ifstream fin("cmlsc.in");
ofstream fout("cmlsc.out");
const int DIM = 1025;
int n, m, a[DIM], b[DIM], dp[DIM][DIM];

void afisare(int i, int j)
{
    if(i == 0 || j == 0)
        return;
    if(a[i] == b[j])
    {
        afisare(i - 1, j - 1);
        fout << a[i] << " ";
    }
    else
    {
        if(dp[i - 1][j] > dp[i][j - 1])
            afisare(i - 1, j);
        else
            afisare(i,  j - 1);
    }
}

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++)
            dp[i][j] = (a[i] == b[j] ? 1 + dp[i - 1][j - 1] : max(dp[i - 1][j], dp[i][j - 1]));
    fout << dp[n][m] << "\n";
    afisare(n, m);

    fin.close();
    fout.close();
    return 0;
}